Cool Science

Atsushi Tero of Hokkaido University grew the slime mold Physarum polycephalum in a flat wet dish. He placed the mold in a central position representing Tokyo, and he placed oat flakes in the dish corresponding to the locations of other major cities in the Greater Tokyo Area. As Physarum avoids bright light, light was used to simulate mountains, water and other obstacles in the dish. The mold first densely filled the space with plasmodia, then thinned the network to focus on efficiently connected branches. The network strikingly resembled Tokyo's rail system.

I normally stick to physics but this is incredibly cool.