Help ID'ing a crab, and any information on it.

[FaRico]

Hi Reefers

So I was eating breakfast this morning watching the tank when I saw one of these come out of a hole in a rock. I got a good look, then it scurried back into the rock. Kind of looked like a white tarantula . Are they good/bad? Any help would be great. The pic is not of the exact one I found, this is of a pic from google. Couldn't find any good information on it.

Thanks in advance.