A brainless yellow slime mold can solve a maze

Physarum polycephalum has no brain, no neurons, and is a single sprawling cell — yet when researchers placed food at two exits of a maze, it retracted from every dead end and left only the shortest path connecting them. The 2000 experiment showed that a basic feedback loop of growth and retraction can solve a real optimisation problem, no nervous system required.

— Toshiyuki Nakagaki, Hiroyasu Yamada, Ágota Tóth, Maze-Solving by an Amoeboid Organism — Nature, 2000