I believe it's a crinoid. It's related to a starfish but feeds through the water column. It also moves. Fun Fact (I think this is true) they were the precursors to starfish. You can actually find crinoid skeletons in the limestone all over the place here in utah, though it's very difficult to find a "roots" or the "head" but the stems are all over the place.
I would suggest never purchasing one though since they feed through the water column they require a ton of food. They are sort of like a cross between a sea fan and starfish.
Micah
Edited by Sculpin - December 01 2010 at 3:18pm