Unfortunately neither were the crab I have. I have researched a little more and it seems to be possibly a purple xanthid. Sort of similar to this http://www.chucksaddiction.com/xanthid1.jpg
So far he hasn't damaged any coral or polyps, so I'm leaving him alone, for now. He's nocturnal and very skittish. Thank you very much for the help! If you know anything on xanthids, I wouldn't mind the information.