I, Slime Mold
So he and his colleagues set up an experiment where they laid out 36 bits of food in a pattern corresponding to cities in the Tokyo area and put a slime mold, Physarum polycephalum, at the spot corresponding to Tokyo.
As they report in Science, after 26 hours the slime mold had created a series of tubular connections that matched, to a great extent, the rail links among these cities. The researchers found that the slime mold network was as efficient as the rail network, it tolerated breaks in the connections just as well, and it was created at reasonable cost to the organism.
Cool.
Any kind of research can be argued to be useful to at least some extend, in any case the time spent to derive this result can definitely be better spent.
So Bacteria and humans both aim to achieve the shortest route? What do you know?!