Good crab or bad crab?

[nemonick84]

I've got a crab that hitchhiked in on my xenia I recently purchased. He's white with small grey markings on his back. It looks somewhat like a porcelain crab but I'm not entirely sure. I'd post a pic but he always stays hidden deep under the polyps of my xenia - I only see him come out breifly from time-to-time. Lately I've been noticing that some of the polyps are missing some of their appendages and today I caught a glimpse of him stuffing some of the polyps into his mouth. Not sure if he's cleaning stuff off of them or if he's eating them. Given their appearance lately I'm starting to lean towards eating. Any help would be great.
Thanks
Nick

 

[reefD]

i think you answered your question. set up a trap and get him out asap.