|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.