What is a chiniderm?

It seems there may be a typographical error in your question, as "chiniderm" does not correspond to any recognized term in Biology or related fields. If you meant "echinoderm," then echinoderms are a group of marine animals that include starfish, sea urchins, and sea cucumbers, characterized by their radial symmetry and a calcareous endoskeleton. They are known for their unique water vascular system, which aids in movement and feeding. If you meant something else, please provide clarification!