Look at these images at the address below. They are called omarolluk's omars for short. I have A LOT of of them. I'll bump the rocks with holes in them thread for you.
great info and link!! I've found several over the years...all were granite. Have always wondered why the holes were spherical on the inside and not cylindrical, abrasion does explain that...but I still lug them home just incase! LOL!