As far as the explosion was concerned, I resumed the concept of atomic bomb, which did not explode on the ground, but at 600 meters above it. Regarding the shape (in this frame the shape still had to be completed), I was inspired by an 18th century illustration of the artist and biologist Ernst Haekel, posted in the comments. Evolutions and movements of black matter are determined by various magnetic fields. The kaleidoscopic shape of falling bombs, is inspired by the phenomenon of Chladni plate (picture in the comment).
Ernst Haekel:
Chladni plate: