Is this hermit dangerous to a reef tank? (pic)

[boardsurfer]

I've had this hermit crab for a while, but now I'm making the transition from FOWLR to a reef tank. What I'm wondering is:

What is the name of this hermit crab, and is it harmful to a reef tank?

He has white rings around the ends of his legs and has two rather large pinchers. It looks as if it scrapes and scratches the coraline algae off of the LR, but I've got enough LR where it didn't bother me. But now I have some yellow polyps in the tank and I'm worried he might munch on them.

Anyone know? Thanks in advance...

 

[schoeplein]

More than likely he's just eating detritus off your rock - not coralline. I would say he's safe - the only issue you'd have is with him climbing on your coral and his shell causing damage (if he's large enough, anyway).