Instead of blood, sea stars have a circulatory system made up primarily of sea water. Seawater is pumped into the animal’s water vascular system through its sieve plate (madreporite — light-colored spot on the top).
When it catches food the sea star then pushes its stomach through its mouth outside and then digests the animal and slides its stomach back into its own body.
Sea stars also have eyes at the end of each arm, the more arms the more eyes. Each sea star eye is very simple and looks like a red spot. They are mostly just for sensing light.
And when they walk on land it looks like an alien.