How to safely get a porcelain crab out of a rock

[tlhood]

I have a piece of base rock (figures) that I want to take out of the tank and fresh water dip since there are some starfish type things in it that I can't identify. Seriously their legs are like as thin as a strand of hair but they stretch out across my sand for a good half a foot. Since I can't ID them (they don't match anything I've found on micro brittle stars) I want to get them out to make sure they don't start snacking on my snails.

Anywho, I have a bunch of bumblebee snails and a porcelain crab that live in the inner caves of this rock. The bumble bees are easy enough to get out since they come out during feeding time, but the porcelain is very shy and usually sits at the front of a cave and darts in as soon as it sees movement. Is there a way to get it out of the rock safely without killing it?