Crinoidal fossils are pieces of animal skeleton fossils from an estimated 245 -570 million years ago. Crinoids are ancient cousins of starfish, sand dollars, sea urchins and sea cucumbers. Featuring a root-like base, a long stem-like column and then a head that resembles a flower, they look more like plants than animals, and are sometimes referred to as "sea lilies." Crinoids were so abundant that they sometimes formed vast underwater "gardens," leading to the beds of fossils we find today. Completely preserved fossils are rare, as we usually see their skeletons as a conglomeration of fossils.