Clicking in the tank often isn't mantis shrimp, but ends up being pistol or popping shrimp. These look more like a small lobster, only with just one large claw (the popper) and a smaller one for feeding.
The "popping" noise is primarily used for defense, but I have seen them trap small shrimp and fish in their burrows and then stun them enough to overpower them.
Most remain fairly small and are relatively harmless over the long run....an added plus, however is that many of the shrimp gobies will move in and form symbiotic pairs that are fascinating to watch.
Pistol shrimp are common here in Florida, and I was concerned about their pairing with gobies from other seas, but found that it seems to work in the majority of cases (although it may be sometimes more of the fishes idea than the shrimps)
