coelenterate marine animals, primarily of the class Anthozoa and sometimes of the class Hydrozoa (of the suborder Hydrocorallia). Most corals form a calcareous or, less often, horny skeleton of varying shapes. Accumulations of madrepores form the basis of coral reefs. Coral is also the designation given to the skeletons of animals of the order Gorgonaria, such as red coral and black coral, from which necklaces and other types of jewelry are made.