The World's Most Expensive Fungus | NOVA | PBS

- Believe it or not, one of the world's most coveted status symbols is a caterpillar with a fungus growing out of its face. I'm Anna, and this is "Gross Science. " On the Tibetan Plateau in the Himalayas, ghost moth caterpillars live underground, keeping warm and eating plant roots, till they turn into adult ghost moths. - Mmm, cozy. - That is, unless they get infected with the fungus, Ophiocordyceps sinensis. The fungus enters a caterpillar's body in summer or autumn, and it starts to grow in threads through the caterpillar's organs, eating it from the inside out. Brainwashed by the fungus, the caterpillar crawls upward, until it's just below the surface of the soil, where it dies. - Resistance is futile. - In the spring, a long brown fungal stalk bursts from the caterpillar's head. It pops through the soil to send out its spores, which infect other caterpillars. And the circle of life and parasitism continue. Now, you might think that's the end of the story. But people scour the meadows where the fungus grows, hoping to harvest these infected corpses. Why? Well, a pound of the fungus, called yartsa gunbu, can be worth tens of thousands of dollars. In fact, it's probably the most valuable fungus in the world. That's because it's used in traditional Chinese and Tibetan medicine to slow aging, cure cancer, and treat all kinds of other diseases. It's even sold as an aphrodisiac. The science is still out on whether eating yartsa gunbu actually does anything good for your health. But harvesting it is definitely bad for the fungus. It's a huge status symbol in China, and people have collected so much Ophiocordyceps sinensis, that it's now in endangered in some places. And this isn't just a problem for the parasite, or for the people who eat it, or brew it in tea. Yartsa gunbu is a big part of the economy in places where it's harvested, like Tibet and Nepal. So local communities are trying to figure out ways to sustainably harvest the fungus. Because for them, this is one parasite that's worth protecting. I still feel kind of bad for the caterpillar though. Ew.