Want to know about Pistol Shrimp?

I bought a pistol shrimp about a month ago. Put him in the tank and haven't seen or heard from him since. He immediately dug a hole under a rock and haven't seen him since he went in. Is is still in there, ya think? Every once in a while I'll see small holes under rocks, but with other diggers in tank i can't tell. Any suggestions.

I think pistols are so cool, but haven't gotten to enjoy mine yet....