New reefer. 32g bio cube. Just finished cycling and added some clean up crew yesterday from my LFS (4 astria, 10 blue legged crabs - that’s all they had available). This morning 3 crabs appear dead, one shell has holes in it, and I see this freaking thing. what the heck is this?! I put on some gloves and tried to grab it but the flipping thing was fast and darted below the rock.