Sea fans, sometimes named horn corals or bark corals, count around 1 200 species that meet each other in all the tropical and subtropical seas. In the shape of a fan, often bright colours (red, yellow, purple), their skeleton is formed by a flexible and hard substance. Like other corals, sea fans are generally fixed to hard substrates, but some species can be found on a sand or mud ground. Here is a very nice natural gorgonian in a black version.