Yeah Pistol Shrimps rock, they are ambush predators and are also opportunistic.

I've never observed my one actively hunting, though he does spend literally all day perfecting his burrow, he regularly constructs doorways out of empty shells and even live snails, it's quite entertaining watching him pick up the same snail several times when it's just trying to get away.

Also its relationship with its Goby fish partner is great to watch, they make a great little team.