FINS ON. WET SUIT ZIPPED. Goggles stuck fast like a leech. My guide’s words rattle my brain as the South Pacific fills my view. “You won’t hurt the coral, but the coral will hurt you.” But isn’t coral the one in trouble? I launch willingly into what the imperious imperialist Captain James Cook some 250 years ago called the “insane Labyrinth.” Here a palace, forged by a quiet army, burst through the hull of his ship.  The skirmish left Cook’s haggard and hungry crew, teeth already wiggling from scurvy, marooned for weeks in far northeastern Australia as they repaired the embattled Endeavour, to wander a strange and unfamiliar coastline they were lucky to reach, in bouts of conflict and reconciliation with the ever gracious Guugu Yimithirr people.

The water around me is green and murky, like the sky’s unnatural pallor before a tornado. Giant clams the size of V6 engines pucker up from the seabed. Bird-bright parrotfish file through the reef in procession, nipping chunks of coral with their fused teeth. Massive table corals roll out a banquet below me. Elkhorn and staghorn crowd their margins, like hands reaching up in worship. I fly over forms most marvelous: brains, mushrooms, organ pipes. A living specimen of that last one, Tubipora musica, made Cook’s onboard naturalist Joseph Banks admit they weren’t looking closely enough. “I have often lamented,” Banks wrote in his journal, “that we had not time to make proper observations upon this curious tribe of animals but we were so intirely taken up with the more conspicuous links of the chain of creation as fish, Plants, Birds etc. etc. that it was impossible.”

Then I see them: bone-white bouquets arranged like baby’s breath. Alive but moribund, cut flowers blooming on borrowed time. A mass bleaching event has recently overexposed the reef, made worse by a whirling cyclone and predacious crown-of-thorns starfish. Several meters beyond lies a graveyard of properly dead coral, smothered in something resembling ash. The palace is slipping to ruin.

Our modern ecogrief for coral would be unthinkable to European naturalists in the era when they first decided coral was an animal—not a plant, not a stone, not the hybrid zoophyte (though that neologism may not be so far off). Corals strained the limits of existing categories when naturalists like Carl Linnaeus raced to bring order to a promiscuous natural world in the eighteenth century. People couldn’t easily observe corals as living organisms, even if they braved the dangers of a diving bell. And corals made marine navigation a living nightmare. Europeans were more likely to curse coral, put its dead skeleton on their mantel, or hand a stem of it to a teething child than to think it might vanish. Now, only the Australians like Shane guiding me now, primed by crocs and taipans to always look over their shoulders, seem to grasp coral’s vital, even foreboding potential in an age of such profound loss.

To behold coral in the sea, one must endure a violent whiplash between extremes of scale. Reefs themselves can be titanic. Australia’s Great Barrier Reef, where I am now, is visible from low Earth orbit. The Dolomite Alps, which loom over northeastern Italy like the spine of some buried kaiju, are actually ancient Triassic reefs, pushed heavenward by violent plate collisions under the earth. But look closely at a reef—very closely—uncomfortably, intimately, about-to-get-poisoned closely, and you’ll see amid the shove of waves that every living coral is covered in a blanket of stars. Many are no bigger than the tip of a ballpoint pen. These are not the reef’s residents, but its makers. Every coral polyp, as they’re called, is a mouth and stomach ringed by a halo of tentacles. If they look to you like shrunken sea anemones or upside-down jellyfish, it’s because the three are cousins, together forming the primeval phylum Cnidaria.

When Cook hit the reef, he paid the price for not noticing the background hum of animal labor on which we all inextricably depend yet too frequently fail to heed. The dairy cows who shake in the cold and suffer forced insemination so we can lap their babies’ milk. Freckle-size midges who bring us chocolate by pollinating cacao as they slip in the tree’s tiny flowers. Termites who, when not busy munching two-by-fours, turn soil into fertile pudding and boost our crops. The coral polyps who secrete homes for a full quarter of marine life, in turn feeding millions of people, all while sheltering us from the crushing force of hurricanes and tsunamis, not to mention buoying tourism. If we feel like reducing some of Earth’s longest-lived animals to dollars and cents, experts estimate corals net nearly $30 billion in global economies every year.

I struggle to get a good look at a single polyp as trade winds run the water around me ragged. Animal labor is often invisible, sometimes literally so. William Stukeley—a scientific loser in retrospect, but an esteemed buddy of Sir Isaac Newton in his day—penned a manifesto to London’s Royal Society in 1752, doubting the labor of polyps. He couldn’t fathom that a being so lowly, so slimy, so seemingly insignificant could raise mountains under the ocean. That was God’s job.

But many Indigenous groups have always known what’s what. For in their cosmologies, corals are foundational. In the Hawaiian creation chant known as the Kumulipo, corals are the first animals to emerge from the cosmic void. In the folklore of the Maldives—a chain of islands, ever shifting, made of and by coral—the world has an edge, and mad waters rush over it. As a ship veers toward the abyss in one tale, its desperate sailors hook their line on a giant tree of black coral, known as Dagas, which perches on the point of no return. Coral is refuge. Coral is home. The world ends with coral.

Corals are in fact three things in one: something of an animal, something of a plant, and something of a stone. They make individuality seem specious, interconnection and collectivity the peeled-back reality.

I THINK OF CORAL when I’m swimming through the Pacific, and I dream of coral once I’m back home, half a world away from the labyrinth. To the rest of my family I look like a blur, always scurrying behind the scenes, my thoughts a carousel sped up by an order of three. When my husband and I decided to start a family, I created a new organ to feed my growing child. When she entered the greater world, I gave her my breast. See me now, fluffing my daughter’s pillow so she can drift to sleep in peace, then watching the clock so I know just when to rouse her before the night terror begins. Cutting all the grapes lengthwise in quarters. Studying each sock—Too small? Too worn? Too itchy? I live halfway outside myself. I battle the laundry that somehow always respawns, like the Hydra of classical antiquity.

Did you know coral’s freshwater sister, genus Hydra, will regrow like a plant if you cut off a tentacle, or become two whole monsters if you chop it in half? Would that I were a coral polyp: six or eight arms to keep up with the load. An army of other Whitneys to take charge when one buckles.

Corals are in fact three things in one: something of an animal, something of a plant, and something of a stone. They make individuality seem specious, interconnection and collectivity the peeled-back reality. In a bit of semantic mischief after their brush with Captain Cook, they are called “colonial organisms,” forming massive webs of indistinguishable polyps. Holobiont, a Greek mash-up for “whole living being,” is the preferred term of coral biologists. Polyps conspire with algae hidden in their skin to convert sunlight to sustenance. Remember, bleaching is not when coral dies—not yet—but rather when polyps expel these colorful algal symbionts due to toxin buildup from heat stress. The dissolution of that partnership reveals the ivory armature beneath.

Polyps share signals, sugars, and secrets with other polyps through a net of connective tissue that knits the mass into a superorganism. What they eat is not theirs alone. Nor is what they build. Polyps draw seawater into their mouths to lay down calcium carbonate—the stuff of seashells and marble statues, and all that remains of coral when polyps succumb. The peaks and valleys of this limestone exoskeleton create a psychedelic home for moray eels and octopuses, stingrays and sea slugs, pom-pom crabs, and Christmas tree worms.

For my daughter’s whole life, even when I am gone—though I’ve promised to stay as long as I can so we can race our wheelchairs once every hair on our red heads has turned white—she will carry my cells in her blood. I will always be part of her. And she has always been part of me. As I crouched in my mother’s womb, she was with me already, an egg waiting to unfold. After her first cry in the maternity ward, umbilical cord still laced between my legs, rushing us together, the resident grabbed a pair of scissors and asked, “Are you ready to be separated?”

No one is ready. But I needn’t have worried. My daughter’s cells knock around in my blood even now. Something called maternal-fetal microchimerism makes each of us an ecosystem of the other, neither ever alone. Each of us a whole living being.

LIKE FISH OR BREAD, the label coral disguises complexity. Some corals have nearly a billion polyp clones. Other species are a community of one. The polyps that build colorful reefs are called stony corals. Scleractinians. The word feels harsh, like staccato plucking in my mouth. Eight-tentacled octocorals, so-called soft corals, are but distant relatives; in fact, stony corals are more closely related to sea anemones than they are to soft corals. The sea fans of family Gorgoniidae look like stalks of broccoli run through a hydraulic press. Another soft coral, the sea pens, are looming Roman guards, with each polyp assuming a specialized role: one morphs into a central rachis and root, while the others fan out in graceful plumes to take in water, catch plankton, or reproduce. Divide and flourish. Black corals, the antipatharians, are yet another Bauplan. They are not the state animal of Hawaiʻi, but its state gem.

The tropical reefs our minds tend to conjure by reflex are also misleading. Corals both stony and soft inhabit frigid waters deep on the ocean’s floor, where sunlight will never reach. More than half of known coral species inhabit cold depths. One found near the Mariana Trench was only added to the annals of science last year. It can stand as tall as a second grader. It stoops over, sacerdotal, covered in long polyped tendrils resembling a ceremonial robe. The strands sparkle like sequined tassels. Its Latin species name is chewbacca. It doesn’t seem to belong to this world.

When it comes to boundaries, corals are libertine, unchaste. And I haven’t even told you how they have sex.

Here again, corals have options. Some species can bud like a plant, sending off a miniature parcel of themselves. Even a fragment detached by trauma can settle elsewhere and regenerate anew as a perfect genetic double. But many species crave union with other corals. Picture a marine bacchanal that would make Neptune blush: during broadcast spawning, the ocean becomes a conjugal cloud of egg and sperm gametes, often cued—who said romance is dead?—to the phase of the moon. Other coral sex is far more personal. In the rarer case of coral brooding, a polyp will swallow floating sperm into her mouth, completing fertilization within. Then she spits out the baby, a larval planula looking something like a levitating pine nut, when it’s ready to journey elsewhere by crawling or drifting. Some coral species are swingers: a little public sex here, a little prudish cloning there. Virtually any of these scenarios can feature hermaphroditic polyps. What does coral have to gain by keeping things simple?

The idea of a rational bounded self melts into nonsense when we look at corals. As assemblages, bound by glorious goo, corals radically embody interconnection and cooperation, both within and between species. A century after Captain Cook trembled at coral, the towering socialist thinker Karl Marx found in polyps proof of the power of small things and the promises of collective labor. A contemporaneous tract, anonymously published in a Quaker magazine, waxed on corals: “It is animal socialism of the purest kind.”

But corals are uncomfortable models too—no simple salve that promises a world renewed if we could all just simply get along. Despite their kumbaya image, some corals aggressively consume and displace other coral species, just like we humans do. As oceans acidify, corroding existing reefs and making it harder to build new ones, polyps may leave their communal form and swim away, rugged individuals bound elsewhere, each a nation unto itself.

Human beings are utterly entangled with corals. We rely on them as ecosystem engineers, as the ocean’s breadbasket, and increasingly as pharmaceutical playgrounds. They rely on us to keep their home healthy . . . something we’re failing at lately amid a sixth mass extinction, this one of our own making. They face, as we all face, rising sea levels, ocean acidification, runaway pollution, a warming climate. Corals, in some form, may persist. Perhaps humans in some form too. Yet even if we magically stopped emitting carbon today, many of coral’s most dazzling formations would still meet their end from forces we—not the earth’s dispassionate rumblings—have set in motion. Following a severe heat wave, Florida’s elkhorn and staghorn corals were just declared functionally extinct—a label reserved for when an organism has been too depleted to matter to its ecosystem anymore. It is often a prelude to the big one: extinction proper, gone for good.

What does coral have to gain by keeping things simple?

SOMETIMES, AN INDIVIDUAL BEARS THE WEIGHT of extinction—Martha the passenger pigeon, Lonesome George the Pinta Island tortoise, Incas the Carolina parakeet. These poor souls are called endlings, the last known holdouts of their kind. As a child in the early ’90s, I’d sit down at my computer to watch a grainy video on an old CD-ROM game of what’s thought to be the last thylacine on Earth. It roamed its Hobart Zoo enclosure in restless circles. I’d hit replay and sob to the saccharine oboe synth, knowing neither I, nor anyone, would ever see its giant, synapsid yawn again. Scrolling the video’s YouTube comments today, I see I was not alone. The horror of these extinctions is communal—for the species, and for us, the witnesses. But the main event for the endling is lonely and singular.

Yet not every ending has an endling. The great auk’s likely extinction was a three-for-one deal: In 1844, farmhand mercenaries dressed in oilskins strangled the last known birds—a breeding pair, mom and dad against the world—while their lone egg was cracked. Two generations gone in one morning.

So how does the world end for a superorganism?

In the coral extinctions that are sure to come, a given species may not exit in a simple way, nor with a graceful, televised bow. Marine biologist Karen Neely acquaints me with pillar coral, or Dendrogyra cylindrus, a critically endangered Caribbean species that sprouts up in stately columns, its fuzzy coating of outstretched tentacles evoking a Koosh ball. It’s so animate that researchers bestow names on its more charming clusters: Archie, Bunny, Lonesome Larry. Those three are all ruins now. “I don’t know anyone who works with corals who hasn’t shed countless tears underwater,” Neely tells me. She’s held vigil for some of these named corals and watched them die.

This naturally rare coral, the only member of its genus, has cratered in recent years. Should pillar coral—also now functionally extinct in Florida—go the way of thylacines, the final colony might break down from warming waters or tissue loss disease or even choked by sediment. The violence may be slow and insidious, with polyp mortality fanning out in a slow burn. Algae and other benthos will take over, bit by bit, filling gaps where polyps once danced, making life out of lemons. Or the last polyps may pass together in a flash, for there is always the chance of cataclysm. A hurricane, a cruise ship’s careless anchor, or the weighted bobbins of a menacing bottom trawl could level the last thousand polyps of a species in less than a minute. If one polyp hangs on a blip longer than the rest—say, one who cloned herself to make all the other polyps at her side, polyps who are both her progeny and herself—the ending will still be ontologically muddy. It will not be faced alone. A Lonesome Larry doesn’t die. Lonesome Larrys die.

We have ever vanishing time to unwrite this narrative. Beneath a just-waning August moon, divers like Neely float underwater and wait for pillar coral to spawn. When they do, a cloud of gametes ascends from one living monument, resembling The Pillars of Creation. These divers, sex therapists in fins, collect the floating sperm and eggs. Then they find each other, mix the gametes they’ve gathered, and bring the newborn coral babies and fragments of pillar coral to onshore and offshore nurseries. This “modern-day ark” will keep the species safe. Until after the flood.

In some regions, the last pillar corals are now too scattered from one another to reproduce without human aid. The endurance of any life-form—corals, chocolate midges, termites, Homo sapiens—must be a team effort. Nations and species don’t stand a chance against global extinction if they bank on self-reliance or nativism. Our solutions must be collective, our labor shared, our communities and very taxa interwoven. We need to look out for each other, to mother one another, knowing no one is separate and that progress is incremental, steady, hard-won, at times tedious, at times glorious and moonlit. So that, like the Dolomites, we can leave something lasting long after we’re gone. Something we perhaps didn’t foresee. Something that might make my daughter’s children, and her children’s children, look up.