I don't remember what they're called and I know these guys are tag alongs (no one buys them). I've had them in every reef tank I've had, they're more of a pest I believe. I do not have any in my new aquarium yet. The reason I'm hesitant to throw it in is because in one of my aquariums these guys ate an entire colony of Zoos. I was devastated as it was a blue hornet zoos colony. Beautiful coral! I was thinking about throwing it in my refugium though. Would it be a good addition to clean up crew in my Fuge or should I just flush it? It should stay in my Fuge and not make it to the main display if I do keep it. It came attached to a scarlet hermet I just got for my refugium.