The Buddhabrot, a ghostly figure that emerges from the Mandelbrot set when you ask a different question of it.
The Mandelbrot set is drawn by taking each point on the screen, feeding it through a simple repeated calculation, and colouring that point by whether the result runs away to infinity or stays put.
This asks instead where the calculation goes on its way out. Each particle is given a starting point and run through the same steps, and at every position it passes through, it deposits a little light. The picture is not a map of starting points at all. It is a map of where the journeys spend their time, and the figure appears out of nothing but the accumulated density of those paths.
Points that never escape contribute nothing, so they are ruled out before any work is done. The image builds up gradually over many frames rather than arriving all at once.