As u/CrustalTrudger notes, they're just impact craters. The reason they are perfectly circular is due to energy dissipation. When an object impacts the surface, the energy of impact is spread out equally in every direction creating a circular crater. This happens regardless of the shape of the impacting object. And it's not just impact craters that are circular; if you look at pictures of explosion craters (from mortars or IEDs or volcanoes or whatever) the crater is circular for the same reasons.
SierraPapaHotel t1_j3gv8tt wrote
Reply to How come there are so many indentations on the moon that are so close to perfectly round that they look as if they could have been be man-made? by mightierthor
As u/CrustalTrudger notes, they're just impact craters. The reason they are perfectly circular is due to energy dissipation. When an object impacts the surface, the energy of impact is spread out equally in every direction creating a circular crater. This happens regardless of the shape of the impacting object. And it's not just impact craters that are circular; if you look at pictures of explosion craters (from mortars or IEDs or volcanoes or whatever) the crater is circular for the same reasons.