What are two features do all Echinoderms have?

All echinoderms possess a unique water vascular system, which aids in locomotion, feeding, and respiration through the use of tube feet. Additionally, they exhibit radial symmetry, typically as pentamerous (five-part) symmetry in adults, allowing for a symmetrical arrangement of body parts around a central axis. These features are key to their classification and function within marine ecosystems.