hiding mantis

[lobie-lou]

I've had a snapping sound coming from several locations in my tank but have never seen what is making the sound. Am not losing any creatures in the tank. How long can these things stay hidden. The tank is almost a year old. I've looked in the night too. Can a red stripped hermit crab make that kind of sound?

 

[skattabrain]

a pistol shrimp can make that sound