I love live rock... but what is this?

It's kind of hard to see but it's about the size of a dime.  Canadian, not American so a small dime.  It lives inside a small hole and I only realized it was alive when I poked it with my aipstatia killing hypo.  Startled me when it jerked itself into the rock and disappeared for a bit.  I poked gently though and didn't injure it.
No idea what it is.  hopefully someone can identify.  It looks sort of "bristle" covered and actually might be the size of a quarter but I can only see a little bit of it./Portals/0/activeforums_Attach/2011-02-21_15.32.31.jpg

 

Dang that picture really blows... it's not a crab from what I can tell. It almost looks like it has 5 arms coming to a point with little thorns growing on them. Sort of like a sea urchin that got itself into a hole then started growing too large and can't get out again.

 

lol yeah yeah, forget I asked. /DesktopModules/ActiveForums/themes/_default//emoticons/wink.gif I'll figure it out eventually.. or I'll find my dang camera.