Off the coast of one of the tropical Solomon Islands in the southwest Pacific, researchers discovered a structure that’s been identified as the world’s largest known coral.

When a team of scientists and researchers from National Geographic first discovered the object, they believed it was so large that it must be the remains of a shipwreck. Underwater cinematographer Manu San Félix, however, was able to identify the item as coral upon closer examination.

“I remember perfectly just jumping and looking down, and I was surprised,” he told reporters during a briefing. “It is enormous, the size is close to the size of a cathedral.”

Residing off the eastern coast of Malualalo Island, the approximately 300-year-old coral has been identified as the species Pavona clavus and measures more than 100 feet long – making it larger than a blue whale. Satellite images of the area revealed that the coral was so large that it could actually be spotted from space.

Enric Sala of National Geographic’s Pristine Seas Project, which encourages governments to protect ocean ecosystems through research and exploration, has dubbed the discovery a “happy accident.” Also dubbed the largest single coral colony ever discovered, the team reported that the coral appears healthy and unimpacted by the pervasive coral bleaching events that have been occurring worldwide over the past two years.

Coral is essential for healthy ocean ecosystems, providing shelter and food for shrimp, fish, worms, and crabs. Unlike a reef, which consists of many colonies, this coral is one single organism that has grown continuously for centuries.

Due to its age, the coral also acts as a window, giving researchers a glimpse into the oceanic conditions of the past. The team hopes to see more marine protected areas (MPAs) established globally through discoveries like these.

“Just when we think there is nothing left to discover on planet Earth, we find a massive coral made of nearly 1 billion little polyps, pulsing with life,” stated Sala.