Chaga is a parasitic fungus that infects its host trees with white heart rot, primarily birch, which causes the tree’s trunk and limbs slowly decay from the inside. The fruiting bodies of Chaga are rarely seen as they form underneath the bark of its host trees, the large black conk we see on the outside of a tree is actually a mass of mycelium, made black by its high melanin content. Chaga is best known for its antioxidant properties and for its ability to be a very consistent fire starter used by aboriginals for centuries.