What are echinads?

Echinoderms are a diverse group of marine animals characterized by their radial symmetry and a unique water vascular system. This phylum includes organisms such as starfish, sea urchins, sand dollars, and sea cucumbers. Echinoderms have a hard calcareous endoskeleton and exhibit various forms of regeneration. They play important roles in marine ecosystems, contributing to the health of coral reefs and ocean floors.