Chaga is a hardened, blackened, crusty formation that looks like a snout or nose coming out from the tree. Do not harvest Chaga smaller than a grapefruit size ( 5/lbs to 10/lbs). Leave these smaller ones to grow for a couple more years. Chaga has been called a “tree cancer” since it will eventually kill its host tree, however, it isn’t completely known whether it occurs to help prolong the trees life or if it is actually cancer to the tree. Chaga has attracted interest for centuries in fighting human cancer and other diseases.