Researchers in Hawaii recently discovered that coral habitats found at intermediate depths between 30-150 meters (about 100-490 feet) host some of the same species that live on coral reefs in shallower waters.
These coral communities are light dependent, but thrive at depths where sunlight penetration is low. The scientific name for the area where these coral communities are found is the mesophotic zone - 'meso' for middle and 'photic' for light.
via Mesophotic Coral Ecosystems Found to Host Species from Shallower Reefs.