Fomes fomentarius

Fomes fomentarius (formerly Ungulina fomentaria or Polyporus fomentarius) is a bracket fungus often named horse's hoof fungus or tinder fungus. It can be found in North America and Europe, typically on birch, but also on beech. A single tree may bear many fruiting bodies.

Whilst inedible, it has particular use in fire lighting, since the tissue of the basidiocarp can smoulder for several hours. This ability was exploited by ancient nomadic peoples to transport fire. Amadou can also be prepared from a velvet-like trama layer. The thickness of this layer varies greatly from fungus to fungus.

http://botanika.hit.bg/gy/gy_6.htm
http://en.wikipedia.org/wiki/Fomes_fomentarius