Crinoids, also known as sea lilies or feather-stars, are marine animals that make up the class Crinoidea of the echinoderms (phylum Echinodermata). Crinoidea comes from the Greek word krinon, "a lily", and eidos, "form". They live both in shallow water and in depths as great as 6,000 meters. Crinoids are characterized by a mouth on the top surface that's surrounded by feeding arms. They have a U-shaped gut, and their anus is located next to the mouth. Although the basic echinoderm pattern of fi… (More on Crinoidea)