To determine just how efficient a mold-designed traffic network will be, researchers ran a test against a preexisting model: Tokyo’s train network. On a map of Japan, bits of food were placed in a pattern representing major cities. The larger the city, the bigger the oat flake was used in its representation. Then, researchers impregnated the Physarum polycephalum mold on the flake representing Tokyo. Finally, they played the waiting game.