pentameral

— All echinoderms share the following characteristics: (a) a pentameral radial symmetry in adults, imposed on a bilateral larval symmetry, (b) a unique water vascular or “ambulacral” system, comprising a network of fluid-filled canals, that serves functions in feeding, gas exchange, and also in locomotion, and (c), a stereom, a mesh-like endoskeleton comprised of calcite (calcium carbonate) plates and pores covered by a thin epidermis [20 ].