An avid beachgoer may search for sea urchins, brittle stars, or even sea cucumbers. An underwater diver may have the luck of finding a sea lily. These organisms might not look alike but they all belong to the Phylum Echinodermata. Generally, echinoderms are pentaradial. In other words they exhibit five-fold symmetry.
Most echinoderms are mobile unlike many of their pentameral peers.
An internal water vascular system facilitates movement. The vast majority of echinoderms are bottom dwellers. Observe the pentameral symmetry in Brissidae , a member of Class Echinoidea.