That is a bit weird. The coatings I have witnessed were paper thin and uneven.
Spheres like these are hard to reproduce naturally, they would need a bit of help from a lack of gravity perhaps.
Or some out of my mind type assumption.
Perhaps a huge explosion of molten matter from a meteorite of large size. the ejecta then would cool in a weightless environment.
” a huge explosion of molten matter from a meteorite of large size. the ejecta then would cool in a weightless environment. “
Why “weightless”? Lead shot is made by dropping in a tower that is in a gravity environment, It’s the gravity that makes them spherical, isn’t it?
From Wiki;
“Molten lead would be dropped from the top of the tower. Like most liquids, surface tension makes drops of molten lead become near-spherical as they fall. When the tower is high enough, the lead droplets will solidify while still dropping and thus will retain their spherical form. “
So maybe molten metal falling from space into the gravity field of Earth created the spheres?