Well,I think I know what happened to my missing goby.Tonight while looking into the tank with a light,I spotted a blue lobster looking critter,I think it might be a mantis shrimp

It's wedged in a crevice under the biggest rock in the tank,so it's going to be hard to get at.
What do I do to make one of those traps?Should I just leave him be(could it be another kind of hitch-hiker?)I dont have a camera to take a pic.
On the plus side,the rock is near a year in the tank and I'm still finding differant things(everything from crabs to sea urchins

)
Jim