Tinder Polypore with spores expelled, Berghem, the Netherlands

"Fomes fomentarius" is a species of fungal plant pathogen found in Europe, Asia, and Africa. The species produces very large polypore fruit bodies which are shaped like a horse's hoof and vary in colour from a silvery grey to almost black, though they are normally brown. It grows on the side of various species of tree, which it infects through broken bark, causing rot.