How is the body of a echinoderm protected and supported?

Echinoderms, such as starfish and sea urchins, are protected and supported by a unique internal skeleton made of calcareous plates, known as ossicles. These plates form a rigid structure that provides both protection and support while allowing for flexibility. Additionally, the outer layer of many echinoderms is often covered with a tough, spiny skin that serves as an additional defense against predators. This combination of skeletal support and protective skin enables echinoderms to thrive in various marine environments.