Need help with mystery noise

[pirate]

Sometimes it just one, and some times its a lots. I think it depends on what he is doing? If he is out looking for food then usually its multiple snaps. He stuns what ever he is going to eat, and then eats it. But if its in a shell like a snail or hermit crab be breaks open the shell with his claw. I have found broken shells arouond the old tank. If he is making his home (under the rock work) he will push out all the sand in to piles by his entrance to his home, and he will drag little bits of rock and empty snail shells to make a solid entrance way for him. And then its usually just 1 snap.
Before I moved into the new tank I use to see my shrimp and gobi all the time. It was neat to see, if you saw the gobi you saw the shrimpa few mins later and the gobi would just watch him to make sure it was safe for him.