Got it. Thanks! Never occurred to me that the round stones would’ve been buried. Duh. ;)
Even then it can still be challenging sometimes though. You have to be lucky enough to find a ravine that cut down into a layer of those Cobbles. That is why ancient man had their common quarry locations they had to travel to in order to find the good stuff. And this is why rock was the first bartering currency. Those who couldn’t get to the Quarry had to trade for rock from those who could. :)