Maybe some previous owner had to saw out a stuck seat post, and just let the aluminium bits fall into the BB shell?
Glad to hear you're on the mend. In the '90s, my brother cycled across Michigan, from Detroit to Sleeping Bear Dunes park, with his ankle in a cast and crutches strapped to the frame. Took the ferry from Ludington to Manitowoc WI, got back on his bike, I picked him up (by car) in Port Washington, and we had a blast at IrishFest in Milwaukee.
That looks like a Chinese finger torture trap for giants, re-purposed as a bottle recycler.
