Here you go! This explains it well. https://en.wikipedia.org/wiki/Close-packing_of_equal_spheres https://en.wikipedia.org/wiki/Close-packing_of_equal_spheres

Here you go! This explains it well. https://en.wikipedia.org/wiki/Close-packing_of_equal_spheres https://en.wikipedia.org/wiki/Close-packing_of_equal_spheres Imagine stacking marbles. They'll naturally fall into a hexagonal pattern as the most likely way of naturally stacking.