Sometimes a coin makes a great tool when nothing else is handy. Folks used them for washers, gears, pie cutters and more.
I was also thinking it was maybe done deliberately for some purpose, but who knows what that would have been. It's shaped like an outlet plug for example, but it's way too small for anything related to that. Nickel is a good conductor. Or somebody just screwing around with their vice.
…like a screwdriver. A nickel then fit perfectly into the straight-slot screws of the era…other denoms too, but a silver dollar was probably too thick and you would think you would not use a gold coin for that purpose.
Probably kids playing. As a kid, more than once, I put a coin on a railroad track. Also shot a few. Cal
Even today I use coins as shims to even out the microwave and a wobbly floor lamp. They are cheaper than any alternatives.
When I see stuff like that I think about when I was a very very young collector. Every cent in my Whitman was polished with an eraser. I just didn't know any better.
Now you've got me wondering how much current a Zincoln would pass before it melted. (Melting could make things worse -- but zinc boils at a relatively low temp, so maybe it wouldn't be an issue long enough to matter.) Oooh... just realized I've got a small spot-welder that sends pulses of several hundred amps! I may need to do some experimenting.
The beefiest controlled-current source I have will only go up to 30 amps. I tried that just now. The Zincoln got hot - within a minute, it was around 250˚F - but not hot enough to melt. I could hook up jumper cables to a car battery and hit it with that, but I'm not especially tempted. At least not right now.