Clicking sound...

[CobiaLover]

They don't have to be very big (depending on the thickness of the glass.) In the summer months I handle mantis shrimp, or as we call them Sea Lice, everyday. To understand their power you need to see one(a dead one) up close. They look a little like the Mike Tyson of the sea and have razor like things on the end of their front legs/arms. My only advice is if your tank is glass get it out of there! And make for darn sure that it is dead before you handle it bare handed. They have a few other nick name that you may want to keep in mind: Knuckle Busters and Thumb Splitters

 

[fuzzydwarfs]

is there any other critter that makes the "glass cracking" sound...my tank "cracks" in the evenings and Im sleeping with one eye open just waiting for the gush of 160lts of water to hit the floor...I was thinking that the snails on their way round the tank might make that noise...

JO...

 

[Germanman]

as said earlier in this thread pistol shrimp make clicking noises as well, but they are short and rapid.