This is like something I found last year I called a "whatzit" Only this time it has wings growing, and I think I can see a body and legs under there.
Found on bottom of rock, in creek. Top of rock dry, but it appears that these things are submerged.
I accidentally washed the pants with the paper that had the size on it, so the number isn't exact.
whatzit from '08 (now I can see the wings on this one too, wasn't apparent before)