click click click!

[Samw]

Here's my pistol shrimp trap. It also catches hermit crabs, emerald crabs, etc. In the first 2 pics, the pistol shrimp would be able to get the bait without entering the trap and then make the escape with the food. So, I made the ramp higher. The shrimp was not as lucky the 2nd time around and you can see him in the trap in the 3rd pic.