Crinoid Fossils for Sale

Crinoid Fossils for Sale.  Crinoids are marine animals that make up the class Crinoidea, one of the classes of the phylum Echinodermata.  Echinodermata includes the starfish, brittle stars, sea urchins and sea cucumbers.

Those crinoids which, in their adult form, are attached to the sea bottom by a stalk are commonly called sea lilies, while the unstalked forms are called feather stars or comatulids, being members of the largest crinoid order, Comatulida.

Adult crinoids are characterized by having the mouth located on the upper surface. This is surrounded by feeding arms, and is linked to a U-shaped gut, with the anus being located on the oral disc near the mouth.

Although the basic echinoderm pattern of fivefold symmetry can be recognized, in most crinoids the five arms are subdivided into ten or more. These have feathery pinnules and are spread wide to gather planktonic particles from the water.