>>67266
Speaks more of our "intuition" that natural objects tend to be rounded, but that is mostly an effect of the erosion processes in our atmosphere, and that normally things form geometrically in the universe. Not sure why he would need to average grains for that point.
Lunar dust comes to mind, how its sharp and pointy due to low gravity/not atmospherically eroded.
Its also interesting how there is a bound of size before bodies in space become rounded by their own mass, and there is a lot of weird shaped mid-sized rocks, but bigger things are round.