Although he’s obsessed with finding new uses for mushrooms, Stamets is also a passionate scholar of ancient mycotechnology. He often wears one example: a traditional Transylvanian hat made of amadou, the spongy inner layer of horse’s hoof fungus (Fomes fomentarius), which can be processed into a warm, feltlike fabric. Highly flammable, amadou has also served as tinder for flintlock guns and prehistoric campfires. (Ötzi, the 5,000-year-old “ice man” found in an Alpine glacier, was carrying the stuff in his pouch.) Its absorbent and antimicrobial properties made it ideal for dressing wounds and preserving foods. And amadou was the first medicinal mushroom on record: “Hippocrates described it in 450 B.C. as an anti-inflammatory,” Stamets notes.