For small meteoroids, 90% of the mass is lost to ablation as they comes through the Earth’s atmosphere. Edges, “corners,” rough surfaces, and any other protuberances are the first parts to ablate away. Put an ice cube in water and wait for 90% to melt. The “cube” that’s left will have no edges or points. It’s like that with meteorites.
Protuberance is a funny word that means a thing that protrudes or “sticks out” from something else. If a stony meteoroid had a protuberance in space, the protuberance would be the first thing to break off or ablate away as the meteoroid passes through Earth’s atmosphere.