Hi could some kind person please help me i am a new beginner with marine fish i have just set up a tank ..at the moment i have just live rock and a couple of small coral ie leather glove and green mushroom .2 blue legged hermit crabs and 3 turbo snails......the problem is i bought a new piece of live rock the other day and i keep seeing these legs peeking out of one of the holes but mainly at night ....so i havnt had a really good look at it the best description i can give is as follows...........very pale brown body with fairl longish cream and browny banded legs that seem to be spiny or furry now i know it is deffo a crab but was hoping some one could help me out a little as he is obviously a hitchhiker and dont know what he is exactly or if he is beneficial or harmful to my aquarium.....sorry the description is a bit sketchy but its the best i can do..thanks in advance carl ![Smile :) :)](https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f642.png)
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