A famous fractal in mathematics, named after Benoit B. Mandelbrot.
It is based on a complex number equation (zn+1 = zn2 + c) which is repeated until it:
a) diverges to infinity, where a color is chosen based on how fast it diverges
b) does not diverge, and forms the actual Mandelbrot Set, shown as black
It forms beautiful images.
See: Fractal