Another legendarily royal remedy is the earthworm.

In China, though, it’s not actually known as a worm, but by a far more royal name: Earth Dragon (地龙dì lóng ).

It all started with Emperor Taizu of the Song Dynasty. He ruled from 960 to 976, and apparently had a terrible case of shingles. His royal doctors were all baffled by this persistent and painful skin rash. No one could find a cure.

Finally, a folk doctor was brought in, and—where all else had failed—he simply pulled two earthworms from the ground. He moistened them with honey and sugar, and left them on a plate, where they eventually melted in the sun.

Using that wormy liquid as a balm, he wiped the shingles, and for the very first time, Emperor Taizu felt a cool relief.

But this wasn’t the end of the treatment. Next, the doctor fed the emperor a bowl of earthworm juice—a few days later, he was healed. As a tribute to the night crawlers, the emperor announced a new name for the worms: “Earth Dragons.”

Li Shizhen was also a firm believer in the earthworm’s merits, and noted the creature’s ability to clear internal heat, nourish the lungs and calm asthma, as well as heal aches in joints and skin problems.

Dai Wenjuan, a TCM scholar at Shanxi TCM University, explained that earthworms are still widely used. “They can be applied both externally and internally,” she said. “Eating earthworms can treat asthma, swollen joints and rheumatic arthritis. Externally, it will stop allergic skin reactions.”

Yu Fenghai started his first earth dragon farm, Guangxi Bohai Earthworm Cooperative Society, five years ago in a small village in Southern China’s Guangxi Zhuang Autonomous Region. “We churn out 500 kilos of earthworms every day,” he said, proudly. “Most of them are sold to TCM pharmacies and factories.”

At a pharmacy, one kilo of dried worms sells for about 90 RMB.

Guangxi is not just a hotspot for earthworm farming, but also for earthworm eating. Down there, they’re found in liquor, in pancakes, stir fried with veggies, everywhere.

Farmer Yu’s favorite earthworm recipe is Earth Dragon Soup. To make it, fry 200g of earthworms with 50g of smashed ginger in a pan with oil. Add one spoon of rice wine and 600ml of cold water and let it boil for half an hour. Add salt to taste.

“Earth Dragon Soup can improve circulation and calm down asthma,” said Yu. “And what’s more, it tastes nice—even better than pork soup!”

Pork soup does taste nice, and it’s a frequently-used mask for the salty taste of sea horse, which is one of the most popular, and most mysterious, TCM ingredients of all—one that even rivals ginseng.