Cordyceps (Cordyceps militaris, caterpillar mushroom, dōng chóng xià cǎo)
The cordyceps is a particularly rare and valuable mushroom that is venerated in traditional Chinese and Tibetan medicine because it is believed to be a potent medicinal mushroom with many uses. This mushroom grows mostly in elevations of 3,000m or more about sea level in the highlands of Tibet. Yak shepherds in the region discovered that the mushroom, which the yaks would consume while grazing, increased the vitality and resilience of the animals. Cordyceps have been used as a performance enhancer in traditional Chinese medicine for centuries and likely for over a millenium.
In contrast to many other fungi, the cordyceps does not grown on wood, but rather is a parasite of certain types of caterpillars. The cordyceps mummifies its host and a long brown mushroom grows out of the caterpillar's head which itself looks a bit like a caterpillar: hence the name "caterpillar mushroom". Nowadays, however, cordyceps are mostly cultivated in special substrates or nutrient solutions without caterpillar hosts.