Echinoderm, there are seven main classes of Echinoderms which are brittle stars, basket stars, sea urchins, sand dollars, sea lilies, feather stars, and sea cucumbers. They can be found at every ocean depth, from the intertidal zone to the abyssal zone. Aside from the problematic Arkarua, the first definitive members of the phylum appeared near the start of the Cambrian period.
