I used to have a 200gal bin on the floor that I'd keep feeders in. One year I started noticing that feeders were disappearing from the bin and something was tearing several feeders up a day. I tore the bin down thinking I had a small bass that came in with the feeders. Nope, found nothing. Refilled the bin, placed the feeders back in, and the mystery continued. I figured my mom's cat devised a way to balance itself on the rim and grab feeders since there were never any wet footprints leading away from the bin. So, every morning, I'd put the cat out as I left for school. No good, the massacre continued.
I got permission to borrow a school camera to set up in the basement. (the school wanted the film if it was interesting). What the camera recorded was amazing.
It turned out my Mediterranean octopus was the culprit. Everyday, this 2lb turkey would push the lid of his tank up, crawl along the side of the adjacent tank to the washer/dryer, along the back of the appliances to the workbench's lower shelf, and finally into the bin for some serious munchies. When he had his fill, he retraced his path back to the tank, lifted the tank lid, and eased himself back into his house. No wonder he wasn't eating as many shrimp as he usually did in the evenings.