I have a purple pincushion, and I really enjoy him! He does great at nomming up unwanted algae, and my son loves to pet him when he's close to the surface. Only downside? He regularly runs off with coral frags that aren't glued down. Just sticks them to his head like a hat and makes off with them. If I catch him at it, I can retrieve and replace the frag, but he's dropped a couple down in the rock work, never to be seen again.....