Nice Mib. Not going to ponder on polished this or dug that, but I will say it is quite possible to find a nice marble like that in the wild.
A few years back, a relative (from Canada as well) was kind enough to give me a couple Corks that used to belong to her Mom. I assure you, neither of them would have any interest to add or take away anything to that jar for at least the last 30 years.
Yes, it's possible there were diggers back then too, and some of you might still be here!