What are asterdois make of?

Asterdois, commonly known as sea stars or starfish, are marine invertebrates belonging to the class Asteroidea. They are primarily composed of a central disc and several radiating arms, typically five or more, made up of a tough, spiny skin that covers a skeleton of calcareous plates. Their bodies contain a water vascular system that aids in locomotion and feeding, allowing them to move and manipulate their environment effectively. Sea stars are found in various marine habitats and play important roles in the ecosystem as predators and scavengers.