Nature · Study 030
Coral by Accretion
Random walkers drift down and stick where they touch, growing branching coral from the sea floor by diffusion-limited aggregation.
What you're looking at
Five hundred particles wander at random with a slight downward drift. The moment one touches the floor or anything already stuck, it freezes in place and a new wanderer is released above. Tips catch particles before the sheltered gaps can, so growth runs away into branches and the hollows stay empty.
The idea behind it
Witten and Sander described this process in 1981, and it turned out to model a wide family of real growth: mineral dendrites in rock, frost, soot, lightning channels and some corals. Each structure is a fractal whose detail repeats at every scale.
Try this
Click or tap anywhere to plant a seed there and start a second colony. It regrows when it reaches the surface.
