My skimmer box is a dry as my busted-ass pool but in my old place the strangest things I ever found were a rat and a duckling. The duckling was especially sad as I had rescued all the ducklings from the pool, into which they had jumped during a storm, and could not get back out, by adding a wooden ramp. But it was hand-held and after I removed it one of them must have jumped back in.

I will see if I can dig out the photos of them still swimming round in the storm.