ID this little guy.

I personally wouldn't have a hermit that big in my tank. Cool crab, but could do damage they don't really intend to do.

 

I had 2 crabs that looked very similar to that in a fish only tank for a while. Do a search for Dardanus megistos and see if those images match what you have in your tank. If it does its definitely not reef safe.

 

yeap its definitely a Dardanus megistos.
i think i need a trip to the LFS, to give this little guy back. Ironically he had it where all of his corals were.

 

I will never have any of these in my tank again. I had that same one in my tank and had it kill many large turbo snails I figured hey it needs a new shell. But it then ripped apart my last clam! I figured that it did roughly 120 damage in its stay in the 220 but I took great enjoyment in feeding it to my puffer in the other tank last night when I finaly caught it! Beware of the hermits!

 

lol ty