Yep, tiger pistol shrimp.
He's cool, I have one. You could get him a watchman goby. Love to watch mine build their burrow. Gonna need couple inches of sand for him to burrow and dig in. leave some shell fragments outside burrow hole and he'll pull them in and use them to shore up his burrow walls inside. He can move she'll pieces as big as him! He'll always be digging and extending his burrow and making new entries. Make sure your rock is on the glass, though, not on the sand or he could get crushed or topple your rock when he's digging. He's a very cool addition!! I use turkey Baster and shoot some food into burrow opening during mealtime so that he doesn't kill and eat my snails. During dinner he will usually come near burrow opening and wait for his food. Wow, I'm rambling. Enjoy your hitchhiker!!