Supposely, this is the first commemorative coin minted in Russia in 1757 at the Sestroretsk mint out of cannon metal

But what is interesting is that even up to now, there is no proper proof of such coins, and the only document that mentions this was a document mentioned back in 1763 that a few samples were minted to be presented to Catherine II. You cannot even find a picture of what it could have possibly looked like

And... that is almost 250 years ever since that coin was minted. What has happened to that particular coin?

Could it be possible that, that particular coin has met similar fate to other normal Russian coinages, that were either overstriked, or melted down? Or a very typical story, would be that it was hidden in the backyard of the Sestroretsk mint, only waiting to be found...