Yarsagumba is a unique caterpillar-fungus fusion that occurs when parasitic mushroom spores (Ophiocordyceps sinensis) infect and mummify a ghost moth larva living in the soil. A spindly fungus later sprouts from the dead caterpillar host’s head. Two to six centimeters long, the fungus shoots above the soil, acting as a tiny, finger-shaped flag for harvesters to find. This peculiar hybrid is the world’s most expensive biological resource.

When the demand for, and prices of caterpillar fungus (Ophiocordyceps sinensis, ‘the Himalayan Viagra’, long a part of traditional Chinese medicine) soared, the pastoralists of Golok on the Tibetan plateau where the fungus is endemic dug up, dried and sold the fungus to traders. In the process, these yak and sheep farmers, used to living on the edge of subsistence, became wealthy beyond their imagination.