Crab found in live rock

Well chuffed, just found a hairy crab in amongst my live rock, rock has been in 4 days now and really is coming to life, but this is my best discovery so far, the crab crawled out just b4 lights out time, crawled out of a hole around a few rock ledges then nestled in to a small cave and started nibbling on the rock surface, wasn't a bit afraid of my ugly mug staring at it for 10 mins.