Scientists discover world’s largest coral—so big it can be seen from space
Exclusive photos reveal a sprawling, 300-year-old coral near Solomon Islands, recently discovered by the National Geographic Society’s Pristine Seas expedition team.
From the surface, it looked like a shipwreck, long forgotten on the seabed. But when cinematographer Manu San Félix dove down to take a closer look, he was amazed to find a huge, sprawling coral.
That was the moment the National Geographic Society’s Pristine Seas team says they discovered the world’s largest coral colony during an October 2024 expedition in Solomon Islands, an archipelago in the southwest Pacific Ocean.
At 112 by 105 feet, this mega coral is longer than a blue whale, Earth’s largest animal. It is so enormous that it can be seen from space—yet it was long hidden from view.
The researchers almost missed it too. Its discovery “was really serendipitous,” says Molly Timmers, the expedition’s lead scientist. “It was found the night before we were moving to another section.”
The expedition team say this is the largest coral colony ever recorded. It is made up of nearly a billion genetically identical coral polyps that work together in the colony as if they are one organism.
Although the newly discovered coral is in excellent health, researchers worry about the many threats facing all corals, including global warming and overfishing. They hope this discovery will inspire more protections for marine habitats in the Solomon Islands.
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Billions of coral polyps
“Finding this mega coral is like discovering the tallest tree on earth,” says Enric Sala, National Geographic Explorer in Residence and founder of Pristine Seas, via email. “This discovery rekindles our sense of awe and wonder about the ocean.”
The organism is a type of hard coral called Pavona clavus, or shoulder blade coral because it has columns that “kind of looks like shoulders,” says Timmers.
It is mostly brown with some patches of yellows, reds, pinks, and blues.
Although this individual might look like a gargantuan boulder, corals are animals related to jellyfish and sea anemones. Tiny individual organisms called coral polyps come together in their thousands to form a colony, and many different colonies make up a reef.
The Solomon Islands are part of a region called the Coral Triangle because of its astounding diversity of coral.
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Hiding in plain sight
The researchers believe there could be nearly one billion polyps in this mammoth colony, which is surrounded by sand.
“It's amazing that they've just found this and nobody really noticed before,” says Helen Findlay, a biological oceanographer at Plymouth Marine Laboratory in the U.K., who wasn’t involved in the expedition.
Without scuba or snorkeling equipment to reach the 42-foot-deep coral, the local community may have assumed it was just a large rock. “There's this Western belief that we have seen all of our [coastal] waters,” says Timmers, “but many, many people don't have the masks and snorkels to actually put their heads in the water to see it.”
Three centuries old
Researchers usually use a coral’s height to estimate its age. This 16-foot-high colony is around 300 years old—but it could be even older.
These corals are usually dome-shaped, like a scoop of ice cream, Timmers explains. “This one is kind of flattened and just goes on,” as if melting, she says.
This coral colony is so old it’s lived through major historical events. It would have seen the first Christian missionaries that began visiting the Solomons during the 19th century. It was alive during when the Declaration of Independence was signed, the Second World War, and the COVID-19 pandemic.
“It gives you that wow factor—life really created this and has sustained this massive colony,” says Timmers. “It's like our ancestors are still there in the water.”
Corals under stress
During its 300-year life, this immense organism has witnessed striking changes to the ocean, such as global warming, overfishing, pollution, urban and agricultural development, and ocean acidification. When they visited a nearby reef, the expedition team saw that many corals had already died, but it’s not clear how resilient this newly discovered colony could be in the face of these global threats.
Corals are very sensitive to changes in their environment. “These things are like the polar bear for the tropics,” says Findlay.
As more carbon dioxide is produced and absorbed by the ocean, it changes the pH balance of the water, which can stress the corals. “Our climate crisis is making the ocean warmer and more acidic, and that’s eating corals worldwide, including the mega coral,” says Sala.
Corals use calcium carbonate from the water to create their skeleton so, as the waters become more acidic, it is more difficult for these organisms to grow strong and healthy.
“Just like in people: if you don't have enough calcium or carbonates, you end up with osteoporosis, so your bones start to degrade, and they can get fragile,” says Findlay. “The same can be true for corals if they don't have the right conditions.”
Hope for reefs
With corals around the world being affected by bleaching—77 percent of coral reef areas were subjected to high enough temperatures to cause bleaching between 2023 and 2024— finding such an enormous individual colony still in good health offers hope that corals can be resilient enough to survive the climate crisis.
“You have this life pillar that’s still there,” says Timmers. “It gives you this awe, this hope. Just seeing how big it is—the mega coral—and its survival in an area that wasn’t as healthy.”
Timmers believes the coral’s location—in deeper, cooler waters and protected by a slope and shelf—may be key to its good health. It “is really in an ideal spot,” she says.
The community is hoping the discovery could help their efforts to bring official protections to their waters. In the Solomon Islands, waters are customary, “meaning they're owned by the local community,” says Timmers. They have unofficially protected these waters for around 14 years, and have protection at the provincial level, but want national support, she explains.
For Sala, the discovery of this mega coral reinforces the sense of urgency to protect and restore the world’s wild places.
Global warming of more than 1.5 °C could be catastrophic for coral reefs. Phasing out fossil fuels and protecting 30 percent of the ocean is vital, he says. Currently, just 8.4 percent of the ocean is protected by government regulations.
In the wake of environmental destruction across the planet, seeing something so remarkable made Timmers feel like the coral is crying out: “We're still here. Don't forget about us.”
