I was out with my flashlight today checking out my mysis shrimp and pods in my tank, rather proud of my in tank refugium, and I noticed a small, maybe a 1/4 inch, white crab. I haven't kept in crabs, other than hermits, in this tank so its unlikely that its a baby emerald or something of that sort, although it does have that sort of a body shape. It pretty much kept itself tucked in a whole and I never got to see the whole body, I do have a handful of acros and montiporas, not sure if thats helpful as I thought that coral crab guys had pink legs.