Slime mould – Physarum polycephaum – is a single-celled organism that can always find the shortest path through any maze, or connect different arrangements of food sources, in a very efficient manner with minimum distances. It has a high degree of fault tolerance to accidental disconnection and builds these highly efficient networks without the help of a central command A Japan-based research team explored with slime mould on top of Tokyo’s topographical map and found that the mould itself created a network almost identical to the current rail system.