“Everyone was really excited to take it,” says Peter Zuckerman, referring to  the yarsagumba (YAW-Sheh GOOM-bah) he procured during his week-long trek to  Hungung, a remote Nepalese village near the Tibetan border, one situated in the  vicinity of 27,765-foot Makalu, the world’s fifth-highest mountain. Zuckerman,  who was making the journey to visit the home of a Sherpa named Pasang Lama (part  of the research for his book Buried in the Sky: The Extraordinary Story of  the Sherpa Climbers on K2’s Deadliest Day), had no idea that yarsagumba has  long been used in traditional Chinese and Tibetan medicine, and that it’s a  primary source of income for many inhabitants of the mountainous region, who pay  upwards of a hundred dollars a year for harvesting licenses. Only later did he  find out that the caterpillar fungus—which reportedly sells for up to  $800 an ounce at Chinese herbalist shops in New York—is created when spores of Ophiocordyceps sinensis infect, kill, and mummify a caterpillar, and the  fungus grows out of the head of its host.

While Zuckerman doesn’t recall yarsagumba as being especially unappetizing  (“it has the consistency of a twig and tastes a little like English Breakfast  tea,” he says), the individual who sold it to him remains a vivid memory. “He  was the strangest looking person I’ve ever seen,” he says, noting that the man “looked like a walking tree stump,” not only because he was short and thick, but  because “he had that condition where one’s skin looks like tree bark.” Unwilling  to pay the dealer’s initial asking price of “five million

dollars,” Zuckerman haggled, and ultimately convinced the so-called Tree Man  to trade his supply for pocket change.

The seller’s disquieting physical appearance aside, Zuckerman wasn’t sure he  wanted to ingest the mysterious fungus. But the peer pressure was intense. The  native Nepalese accompanying him on the trek started by extolling the virtues of  yarsagumba, claiming that “it does everything you could ever want,” and regaling  him with stories about how “it makes a stupid man smart and a fat man  skinny.”