Chaga (Inonotus obliquus), also known as cinder conk, is a fungus in Hymenochaetaceae family. It is a fungus parasitic on Birch and other trees. The sterile conk is irregularly formed and has the appearance of burnt charcoal. It is not the fruiting body of the fungus, as many believe, but in fact a big mass of mycelium, mostly black due to the presence of massive amounts of melanin.