I sometimes find plants moved from 1 tank to another randomly.. My 3 year old likes to 'help'.
Then there was the entire canister of flake food that made it's way into the 55g one time (Same 3 year old). Yeah, not a good day.
Ah, and a Glade Air Freshener thing my wife bought, had these little moisture beads, the things that swell to grape size when hit with water, and dry up into BB's when spent. Same 3 year old apparently poured the container of those into my convict tank. Was doing a water change and noticed these transparent egg things moving in the water. Thought I had some freak parasite in the tank laying eggs, and it took a while to figure out what it actually was. Amazingly the fish were fine, and they smelled like fresh linen!
id say spongebob chillin with the wolf fish and the oscars eating captn crunch are the winners in this thread so far.
never really found anything crazy in my tanks other than a time i didnt see my peacock eel for a month and a half back when i had an oscar, assumed he had been eaten but he's still chillaxin in the 75 to this day
ummm my little brother put my goslings in one of my tanks (THEY CRAPPED EVERYWHERE IN IT!!!!) when i went to a friends then when i was at school one day he put the puppie a box of tissues and a slice of cheese in my 100 gal good thing i was just cycling it heeheee
an albino cat when i was young i thought died, heavy planted tank, then all my fish disappeared and my 2" cat was suddenly 11". i was horrified when i first found his hiding spot in a cave that was so well hidden