Until I started visiting the aquarium again it never occurred to me that a starfish was an animal, a living creature that eats. Heck, it didn't even occur to me that they moved. And yep, I did say they eat. If you look at the picture below you can see the shell the starfish is absorbing.
The ones below show it eating seaweed. They have two stomachs - one for digesting and the other can be used to reach out and grab and then digest it's food. I read with some star fish, they use their vascular system to open the shell of something like a clam and then inject their stomach into the shell to eat it.