The widest, and perhaps oldest single coral in the Great Barrier Reef has been discovered—and it’s in excellent health. Those are the findings from the discovery of Mugadhambi, or “big coral” in the language of the Manbarra people, the traditional custodians of the Palm Islands, where the coral has been found.

Discovered near Goolboodi (Orpheus Island) in March 2021, the hemispherical Mugadhambi measures 5.3 meters tall (17 feet) and 10.4 meters wide (34 feet), making it the widest and sixth-tallest coral in the 2,900 reefs that make up the barrier system. After consultation with local tribal elders, it was determined that the coral was completely unknown by the Manbarra people, who were asked to give it a name, being that it resided in their sea-country.

“How it was found is that we were running a citizen science workshop… and were interested in exploring the North Coast of Goolbodhi which is a very remote area often restricted by weather,” says Kaillash Cook who was part of the workshop team and co-author of the new paper.“It was here Dr. Adam Smith found this breathtaking coral and instantly assigned people to take measurements, surveys, and coordinates for the coral.”

Belonging to the genus Porites, Mugadhambi is from one of 16 common coral species that form some of the largest and most important building blocks of nearshore corals, reports Smith.Other enormous Porites have been found in the American Samoa, in the reef around the Green Island off the coast of Taiwan, and Sesoko Island, Okinawa.

Based on yearly growth models, Mugadhambi is estimated at between 421 and 438 years old, an astonishing age to live to amid an ecosystem that’s described as a canary in a coal mine for climate change.

“For shallow water corals, 438 year-old corals are very hard to come by,” Cook admitted. “Australian Institute of Marine Sciences has investigated 328 colonies of massive Porites corals on the Great Barrier Reef and the oldest they have found is 436 years old.”

“While the age is currently an estimate based on measurements of other corals we can safely say that Mugadhambi is one of the oldest structures on the Great Barrier Reef,” said Cook.

“After a torrid few years, the 2020-2021 long term monitoring program of the Great Barrier Reef has found that while COVID has been running rampant above sea level, the reef’s own pandemic, coral bleaching, was hardly noticeable. Hard coral cover has actually increased across all three regions of the reef over the last year.

A review of the environmental events that have occurred in the past 450 years indicates that Mugadhambi may have survived up to 80 major cyclones and centuries of exposure to invasive species, perhaps 100 coral bleaching events, low tides and human activity.

The researchers report that Mugadhambi is in very good health with 70% consisting of live coral, the rest being covered with the green boring sponge, Cliona viridis, turf algae, and green algae.“We found that about 30% of the colony was dead which is a completely natural and healthy occurrence as it supports the growth of turf algae, turtle weed, and sponge which all play important roles in the ecosystem,” said Cook. “This diversity of benthos means that lots of fish are attracted to hide in the coral structure, feed off the turf algae and turn Mugadhambi into a thriving microecosystem.”

“This field note provides important geospatial, environmental, and cultural information of a rare coral that can be monitored, appreciated, potentially restored and hopefully inspire future generations to care more for our reefs and culture,” write the authors.