Loud Clicking noise coming out of the tank

[ScubaSteve]

Originally Posted by Midway

yeah, maybe that explains two of my cleaner shrimps went missing some time ago.

Uh, yup... that might explain it.

I have the same thing in my tank and I've found that many things actually do it. I thought it was my pistol but when I found him dead in the sump. I've noticed my strawberry top snail do this thing where he twists and pulls himself into the glass really quick and makes a cracking sound. He's been incapacitated for the past week and I still hear it. Haven't seen evidence of another pistol or a mantis... so I leave it to one of the mysteries of the tank.. sorta like how a hawaiian rock boring urchin showed up in my tank without having put anything in my tank for over 6 months and the only thing that went in there in 6 months before that was a piece of dead rock that had been sitting dry for over a year. Weird...