Lol! Would have had to be left on there a mighty long time to leave an imprint that will not wipe off, rub off or anything. Thank you for your input.
I think it's toning or damage and not an error. But I'm not an error collector, so I don't know. I'm sure someone more knowledgeable will come along. Better pictures might help.
Maybe less time than you think. Really depends on the conditions around the event. Coins stacked in a drink holder in a hot car accelerate the decay of Zincolns especially. Easy to get those rings in that situation especially if you add a little French fry salt. And stacked coins left around a swimming pool will stain faster too. Witness marks are left behind and tone at a different rate.
What @Kevin Mader said. I see it often. Drinks spilled in cup holder, coins sitting on top of each other. It's damage
It's a deep stain, deep into the paper-thin copper layer. Use some nevr-dull on it. You'll be amazed at how shiny it becomes in very little time/work. We used to use it to shine the brass all over the ship (USS Midway) back in the day.
