Amadou is a spongy, flammable substance prepared from bracket fungi. The species generally used is Fomes fomentarius (formerly Ungulina fomentaria or Polyporus fomentarius) which in English is also called horse's hoof fungus or tinder fungus. The amadou layer can be found on top of the fungus just below the outer skin and above the pores. It is used as tinder (especially after being pounded flat, and boiled or soaked in a solution of nitre) and also used when smouldering as a portable firelighter.
It is also used in fly fishing for drying out artificial flies. It is sometimes also used to form a felt-like fabric used in the making of hats and other items. It has great water-absorbing abilities. Amadou for dry flies can be prepared by soaking the amadou layer in washing soda for a week beating it gently from time to time. After that it has to be dried and when dry it has to be pounded with a blunt object to soften it up and flatten it out.
Amadou was a precious resource to ancient people, allowing them to start a fire by catching sparks from flint struck against iron pyrites. Remarkable evidence for this is provided by the discovery of the 5000-year-old remains of "Ötzi the Iceman", who carried it on a cross-alpine excursion before his murder and subsequent ice-entombment.