Crinoidea is a class of marine animals within the phylum Echinodermata, commonly known as sea lilies or feather stars. They are characterized by a cup-shaped body (the calyx) and long, feathery arms that extend from the body, which are covered in tube feet. Crinoids are primarily filter feeders, using their arms to capture small particles from the water. They can be found in various marine environments, ranging from shallow waters to the deep sea. Crinoidea is one of the oldest groups of echinoderms, with a fossil record dating back to the Cambrian period.
