Echinodermata
The Echinodermata phylum is a very big, famous phylum consisting of well-known ocean creatures , such as sea urchins and sea-stars All echinoderms live in the ocean, with no known recorded exceptions. Echinoderms lack brains, along with specialized sense organs (nose, eyes, ears, etc). Each organism within the echinodermata phylum has four distinct qualities: calcitic skeletons (made from the carbonite material calcite), a water vascular system primarily used for movement, respiration, and consumption, ligaments composed primarily of the protein collagen, and a pentaradially symmetrical body (where the body is organized into 5-different sections that are all the same). There are approximately 7,000 known living species of Echinodermata, with over 13,000 extinct species whose fossils scientists have discovered and analyzed.