What has ten legs and claws?

I don't know, but it's climbing up your ceiling!

Bill Callahan forwards this photo of a tiny critter found on the ceiling of "an old brick and beam building in the Fort Point area" (and then obviously removed from said ceiling). He adds: "It has 10 legs and then the two weird lobster claw type things."

Any guesses as to what it is?

UPDATE: Jef Taylor reports it's a pseudoscorpion. He details the critter and has a really good closeup shot of one that you probably don't want to look at right before lunch.