Echinoderms are a group of marine animals known for their unique radial symmetry and hard, spiny skin. This group includes familiar creatures such as starfish, sea urchins, and sea cucumbers. Echinoderms have a water vascular system that helps them move and feed, using tube feet that operate through hydraulic pressure. These animals are primarily found on the ocean floor and play important roles in their ecosystems. Echinoderms can regenerate lost body parts, which is a fascinating aspect of their biology. They also have a simple nervous system and lack a centralized brain, making them quite different from many other animal groups.