[Bamaguy]

Has anyone ever had a pencil urchin in their tank? I just bought a new piece of live rock and have one as a hitchhiker. Dr Fosters and Smith says they aren't reef friendly but it doesn't say they eat corals, just that they can move around rocks. Should I take him back? I don't have corals yet but plan on it down the road.
I also had a very small golden brown starfish but he ran off and hid before I could get a good look at him.