The reefs are probably thousands of years old, and are home to creatures such as shrimp, brittle stars (a relative of starfish), squid and other animals.

Unlike shallower, warm-water reefs that thrive on sunlight, deep-water reefs are chilly, dark and deep. Temperatures in these reefs range from a brisk 39 to 54 degrees Fahrenheit, and they can be found in deep-ocean areas around the world. Although they are less studied than their shallow counterparts, such reefs are thought to be home to the majority of all coral species.

Because they’re so dark and remote, the reefs are not as studied as their warm-water relatives despite providing massive animal habitats. Only a quarter of the ocean floor has been mapped to a resolution high enough to allow for sustainable ocean management and research. The new maps made on the recent research mission have a high enough resolution to identify living organisms on the sea floor — information that will inform both future research and management of the reserve’s waters and animal inhabitants.

The discoveries come on the heels of an earlier find in April, when scientists first identified a deep-sea reef in the Galápagos Marine Reserve.

“Finding such deep and long-lived reef takes us important steps closer to protecting hidden dimensions of ocean diversity and understanding the role that deep habitats play in maintaining our ocean’s health,” said Stuart Banks, a senior marine scientist at the Charles Darwin Foundation, which funds conservation research in the Galápagos, in a statement news.

The interdisciplinary expedition was part of an ongoing push to better understand the region’s deep-water ecosystem.