Swarming Snips◆ Each enemy in the swarm's space takes 2d8 piercing damage (DC 20 basic Reflex save).
Creatures that fail this save also take 1d4 bleed.
Source: Pathfinder Monster Core 2
Running this fight? Add the hermit crab swarm to the initiative tracker: type its name and the AC, hit points and Perception for initiative fill in, and the book button shows this stat block mid-fight.