Kirby Krackle (Kirby dots)
A field of black, roughly circular dots that are used to represent negative space around unspecified kinds of energy. They are typically found in illustrations of explosions, the blasts from ray guns, and outer-space phenomena.
Kirby dots are named after Jack Kirby, the highly influential comic book artist, whose superhero art frequently featured them. They were developed from the use of a pattern of round black spots to depict smoke or flying debris from explosions, or as a way to manually generate the random patterns that depict the path of lightning strikes.