Also referred to as "Kirby Dots", Kirby krackle is an art technique that consists of small black dots that are typically used to convey great energy. The dots are arranged in close proximity to one another and often overlap, creating fractal-like patterns. In this way they convey the negative space surrounding the energy.
Conventional wisdom holds that Kirby krackle was created in the 1960s by artist Jack Kirby, who lends the technique his name. It has been suggested that Kirby or his inker Joe Simon used similar dots to convey energy as early as 1940. Regardless, the use of the krackle became popular amongst artists, who use it to represent energy in many forms, including cosmic energy, explosions, energy fields and fire.