Right now I have a 30gal that just some live rock in it, no clue what to do with it yet. A 70gal mixed reef/fish and a 30gal tank with a peacock mantis shrimp In the 70, over the past 2 months, I have kept hearing a clicking sound from this one large rock in the corner. Sometimes I'll hear it once, then sometimes I'll hear it 6-7 times in a row. It's not the peacock mantis shrimp in the neighboring tank, I've had my face up against the glass and heard it straight from the rock. So today I heard it 7 times in a row, loud, and I was in my chair checking the tank out, and I'm convinced that there HAS to be a mantis shrimp in that rock. I dunno what else it can be. I also can see 2 snail shells that have been shoved under the rock in a little burrow, and an indent in the sand where something has moved the sand. Don't think its my diamond watchmen goby, he can't go under the rock like that. I've never physically SEEN it, although I've tried many times. So what are some inexpensive ways to draw him out or maybe even try to catch him? If it turns out being a mantis, and I can get him, he will go into my extra 30gal tank and I'll start building a home for him there. I love these guys. What do you guys think?