In any part of the world, you'll find no shortage of expensive delicacies and specialty ingredients. Sea urchins are California gold and white truffles are culinary crack in the US and Europe. In Hong Kong, there's the coveted but bland-tasting shark fin, and even blander birds' nests. Food items with a traditional attachment of medicinal qualities are sold in pricey shops and old school pharmacies all over the country—but above all, one particularly bizarre item stands out: the cordyceps.

It's known as yartsu gunbu ("winter worm, summer grass") by the Tibetans and chongcao ("worm-grass") by the Chinese, and though it's kind of a hybrid, it may be more accurate to call it an infection.

It starts as a spore that spreads in the winter and lands on a moth caterpillar found on the Tibetan plateau. The spore festers within the body of its host until the fungal creep takes over completely. The caterpillar burrows underground as it dies, and the fungus keeps growing, sucking in precious, life-giving nutrients as it bursts through the caterpillar's head. By summer, the fungus is mature, and can be found peeking out of the ground, often hidden by blades of grass. Harvesters need to be extremely careful: they must preserve the leaf-like fungal structure and keep it attached to the yellow caterpillar carcass to show that it's real. Chinese knockoffs don't just come in the form of Louis Vuitton bags and flimsy Ray-Bans; food products and medicines are often faked as well.

Some variation of chongcao is sold in practically every Chinese pharmacy in Hong Kong, and it is said to be tremendously beneficial for the kidney, liver, lungs, throat … the list goes on, as is the case with many traditional Chinese remedies. It's lauded as yet another miracle cure. There isn't any reliable clinical data to back up these claims rooted in Chinese and Tibetan texts—some of which are over a millennium old—but people put a lot of faith in this miracle worm-grass hybrid, and a handful can cost thousands of dollars. In fact, the cheapest chongcao I could locate was US $30,582 per kilo, though they are generally sold per tael (0.0378 kg). That's not quite as expensive as gold, but it's getting close. The more expensive batches, which consist of thicker grubs, can be three to four times that price.

It's one of the most exclusive foods in China. It's also one of the most boring, flavor-wise.

The flavor of chongcao is flat, with a faint hint of sweetness that is usually overpowered by the other ingredients in whatever dish contains them, such as basic chicken soup or medicinal wine.

Nonetheless, its high cost means it's bought and kept as a status symbol, and often gifted as bribes to business contacts and government officials. (The same thing has happened to pu'er, a common fermented dark tea served in practically every restaurant in China. It was only a few years ago when speculation drove prices of aged pu'er to around US $10,000 for several grams. On the other hand, you can still get a pot of great pu'er tea for a few dollars.)

But what do the Tibetans have to say about Han Chinese consuming their most exotic crops? The people who pick chongcao are ethnically Tibetan, and even though they're paid next to nothing to harvest it, the job provides a significant improvement in their standard of living. Nomadic life on the Tibetan plateau, thousands of meters above sea level, can be pretty rough. If plucking a few yartsu gunbu from the ground can pay for some winter supplies, people will. Since the fungus is hard to spot among normal grass, a day's work may only yield one or two dozen chongcao, but the harvesters are paid just shy of US $4 per piece. Obscene profits line the pockets of distributors.

But chongcao have a spiritual significance that cannot be ignored. Tibetan Buddhists believe that they are linked to the supernatural realm, and picking them disturbs the Earth's energy. There is even an old saying: "Picking one gunbu is like killing 18 men."

It may as well be. Continued harvests have changed the physical and political landscapes of the Tibetan plateau. Soil erosion continues to be a problem. Armed conflicts take place when there are disagreements over picking rights. The clashes occasionally leave some harvesters dead.

Chongcao are so popular that their trade continued through the tumultuous revolutions that pepper China's contemporary history, including the Cultural Revolution, when any activity seen as remotely capitalist was suspended. But things are different now. Traditional Chinese medicine has stepped into the consumer spotlight, and is a mature industry that isn't about to slow down. Now chongcao even come in pill form, made from cordyceps mycelia that is cultivated in a controlled environment. They're cheaper and advertised as more in line with the idea of environmental conservation.

As I was being berated by an old woman selling chongcao in one of the Chinese medicine shops near my apartment building—I wasn't willing to part with US $1,500 for a few grubs of worm-grass, and she said I was asking too many questions about her merchandise—a pregnant woman entered and asked for a couple taels. She told me that one of her daily staples is about US $130 worth of chongcao dunked into chicken soup, silkie if possible. I asked if the concoction made her feel different. Healthier, perhaps? The shopkeeper tutted at me but the pregnant woman kept talking anyway. "No," she said, "it's just something the women in our family do, and it seems more authentic than those cheap capsules sold around the corner."