Okay that means that means it was pretty fresh in your memory. Was there an admission price? if so, you should demand a refund and spread the news about this fraud.
Here's the first clue....
...Then came another one and they had 8 sharp sides. Neanderthals had 36 sharp sided tools. Homo Sapiens had 360 sharp edges!
Now think about that 360 edge number, kind of miraculous that it corresponds to the number of degrees in a circle, yes?
If you have kids, see if they have one of those cheap plastic protractors, usually 6" in diameter. If not, the dollar stores have them.
Take a close look at marks delineating one degree. Really small aren't they at the six inch diameter. Now a stone of that diameter, about the size of average saucer doesn't exactly fit comfortably in the hand and with knapped edges all around much less so.
So a smaller diameter stone would be needed to be a usable tool. But that means the arc of 1 degree is even smaller. Plot it out on paper after drawing the 6" arc.
Had Erich von Daeniken found such a stone he would have called it proof that stone age men or aliens had devised a clorkwork gear.
That makes everything presented suspect...sceptical approaches are necessary. Nuff said
Nice job!