Deep inside the tropical rainforests of Borneo are naturally occurring salt licks that provide crucial nutrition to the rare and unusual animals that make the forest their home. In this episode, we accompany mammalogist Hisashi Matsubayashi to one of the most biodiverse habitats on Earth as he studies the salt licks, uses DNA for some detective work, and promotes a strategy to protect some amazing and endangered animals, as well as the forest itself.