I have a pistol that I caught with his head and half his body buried in one of my turbo snail shell's, albit he did NOT break the shell to get to him. From personal experience though, I could not tell the differance between a pistol or a mantis shrimp snapping. I have had both. The only ones I have known in my own system to break open snail shells is the Mantis. I had to wait untill I saw the mantis then quickly reach in and grab that peice of rock out and in a buckett, use soda water premixed with salt to flood the bugger out of the rock. The fizzing gets him out, but with salt mixed with it greatly increases his chances of survival, and dosen't kill bacteria in the rock.