What is it with you and game balls man?
Look... clay marbles dude!
Clay marbles.
He doesn't have a quartz mill ball or some other non metallic ball used for pulverizing material that would not be smart to use metal balls that could spark while tumbling in like gunpowder.
Sorry rock but that's what you bought.
Did you ever wonder why yours doesn't have any patina?
Yours actually looks like ceramic.
They have a visible seam when new..not for long though once put to use
These were found where there was no modern habitation but were ancient sites (coin is for size ref). How could they not make clay balls ? Nice finds. I also have some caucasian made ones. Identical it seems.
You know we have been around this block plenty of times. I will tell you again....I have taken this not once but twice to 2 different places and both places have said it is a true Game Ball. Sorry you think it is a milling ball but you are wrong. Nothing wrong with being wrong at times. Humans do that.