The herb cordyceps has taken the West by storm, with companies like Four Sigmatic and Gwyneth Paltrow’s Goop claiming it’s a mushroom that can boost your energy and heighten your sexual prowess. But the herb is actually a caterpillar fungus and has been used in traditional Chinese medicine for thousands of years. They’re only found on the Tibetan Plateau, so we went there to meet a cordyceps seller and learn more about this industry. In recent years, demand from both wealthy Chinese consumers and new interest from the West has driven prices to thousands of dollars per kilo. All this has led to overharvesting, potentially endangering an herb that’s already threatened by climate change.