What is the most common characteristics for echoderms?

Echinoderms, which include sea stars, sea urchins, and sea cucumbers, are characterized by their radial symmetry, typically exhibiting a five-part symmetry in their adult form. They possess a unique water vascular system that aids in locomotion, feeding, and gas exchange, utilizing tube feet for movement. Additionally, echinoderms have a hard calcareous endoskeleton made of ossicles, which provides structural support. They also exhibit remarkable regenerative abilities, allowing them to regrow lost body parts.