I have one and it is so cool. He builds a tunnle that is about 10 inches long with the main part under a mushroom rock. sometimes he burries the muchrooms a little but they just close up and then open again over his neat little piles. I have a barberpole goby (yellow nose shrimp goby) and they get together well. If I offer the shrimp a piece of calerpa mexicana, he uses his claw to snip off pieces and put them in his burrow. it makes a loud noise and it scared me the first time he did this. He is peaceful and hasnt harmed anything. he is so interesting to watch. He uses his claws like a mini bulldoser and pushed the CC around. then he picks up small shells and uses them to build his burrow, like supports or something.
In summary, he is probably the coolest think I have in my tank.