While the term "coral" may conjure up images of sunny tropical reefs in warm, shallow waters, over half of all known coral species actually live in deep, dark waters. Found all over the world, these deep-sea corals provide habitat complexity to the ocean floor, just as trees turn an otherwise flat, open plain into a varied environment. And, as in the branches of trees, many organisms live among the corals, such as shrimp, crabs, brittle stars, worms, fish, and more. Thus, in the deep ocean, coral communities can essentially serve as important ecosystems unto themselves. These videos represent a snapshot of some of the diverse coral communities encountered during expeditions over the years.