|Sea fans are a form of gorgonian
soft corals that rely on the current for a continuous
supply of food. They may grow up to several feet across,
and are most likely to be found where the current is
strong. As the name suggests, they are broad and flat,
and invariably face the current so as to filter the most
planktonic food. Most soft corals are colored green,
yellow, or brown, due to the presence of single-celled
algae within their tissue.
Though sea fans have a semi-rigid "skeleton" that helps them retain their shape, they are not classified as hard corals, since they lack a hard limestone skeleton. Another simple way to tell the difference between hard and soft corals is by the tentacle count on the polyps; sort corals generally have eight tentacles versus six on hard corals.