Physarum polycephalum, a type of slime mold, grows tendrils in search of food and withdraws extraneous arms to focus on the most efficient paths between sources. Although the American map is just an illustrative model made for Popular Science, researchers in the U.K. have used slime mold to create similar replicas of local roads and railways, backed up by computer models. Andy Adamatzky and Jeff Jones, specialists in unconventional computing at the University of the West of England in Bristol, found that, left to its own devices, the slime mold mimicked a good part of the country's actual road systems. Because slime mold finds the paths that are most resilient to faults or damage, it could be used to make mobile-communication and transportation networks hardier.