You may not have realized it, but urine is your body’s own liquid gold, with many surprising uses and qualities. David Bowie reportedly kept his in the refrigerator. World War I soldiers in Ypres tied urine-soaked socks to their faces as protection against chemical warfare. This smelly, watery, urea-rich fluid comes in different shades of yellow (depending on your water intake) and sometimes green or orange (depending on the medicines you ingest). Here are nine ways in which urine has contributed toward the development of humankind.

1. Urine has been used as an antiseptic for at least 2000 years.

Before modern medicine, when a small wound could potentially end your life, urine emerged as a primitive antiseptic. Pliny the Elder recommended urine for treating scorpion stings, snake bites, rabid dog bites, sores, burns, and many other conditions. He suggested a concoction of stale urine and ashes of roasted oyster shells “for the cure of eruptions on the bodies of infants."

During the Renaissance, an Italian doctor named Leonardo Fioravanti witnessed a Spanish soldier lose his nose in a brawl. Fioravanti quickly urinated on the detached nose before surgically reattaching it to the soldier’s face. And in 1675, The Accomplish’d Lady’s Delight in Preserving, Physick, Beautifying, and Cookery suggested washing one’s face in urine “to make it Fair.” (A writer actually tried this in 2016, with mixed results.)

Urine does have an antibacterial property directly correlated to the concentration of urea, the main metabolite in urine [PDF]. An increase in urea concentration boosts its antibacterial activity. Though other factors like urine osmolality (a.k.a. how watery your pee is), pH, and ammonium concentration do come into play, urea is the MVP.

2. The Romans cleaned their clothes with urine.

In this stall, laundry workers in ancient Rome cleaned clothes with a mix of urine and clay.Dave & Margie Hill, Flickr // CC BY-SA 2.0

Urea decomposes into carbon dioxide and ammonia (that’s what gives urine its pungent smell). Ammonia is one of the central ingredients of modern household cleaners as well, which explains stale urine’s use as a common clothes cleanser in the Roman Empire. By the 1st century CE, vessels for collecting urine were placed at street corners, outside inns, and inside Roman baths, and the emperor Vespasian even imposed a tax on its collection. Some fullonicae (Roman laundries) obtained their supply of urine directly from public urinals via pipes.

At the fullonicae, the urine was allowed to rot for three days before being put into vats with piles of dirty clothes. Fullones (launderers) stomped on the contents to get the dirt out, then rinsed the clothes in water and dried them.

3. Infertility drugs made from two hormones in urine were developed with help from the Vatican.

Piero Donini, a scientist at the Italian pharmaceutical company Serono, extracted two hormones, FSH and LH, from the urine of post-menopausal women in the 1940s. In 1957, endocrinologist Bruno Lunenfeld contacted Serono to run a clinical trial to test whether the hormones could be used to cure infertility. Their biggest challenge, though, was obtaining the thousands of gallons of post-menopausal urine needed to extract sufficient quantities of the hormones.

Luckily, the Vatican was a major shareholder of Serono. Through his nephew Don Giulio Pacelli, one of the company’s directors, Pope Pius XII convinced Italy’s large population of postmenopausal nuns “to collect urine daily for a sacred cause.” Nuns all over Italy donated their urine to Serono, which developed the fertility drugs Pergonal and Menopur. Both are still prescribed today.

4. Urine fueled centuries of wars.

Gunpowder comprises 75 percent potassium nitrate, a.k.a. saltpeter; 10 percent sulphur, and 15 percent charcoal. Until the mid-19th century, saltpeter was either imported from India or made locally from stale urine. The renowned geologist Joseph LeConte detailed the procedure in his manual Instructions for the Manufacture of Saltpeter. First, human and animal urine was collected in pits called nitre beds. Lime and wood ash were added to the mix. Potash, a compound in the wood ash, gave the potassium to form potassium nitrate. The slurry was stirred from time to time and allowed to rot for around two years [PDF], after which it was leached with water and crystallized to get saltpeter.

Europe’s numerous wars prompted a constant need for urine to make gunpowder. In 1625, Charles I of England commissioned saltpetermen to recover urine that had soaked into the floors of stables, and in 1627, his royal proclamation asked his subjects to collect urine in "convenient vessels and receptacles.” A saltpeterman named Nicholas Stephens became notorious for digging up church floors because he believed “that the earth in churches is best … for the women piss in their seats, which causes excellent saltpeter.”

As late as 1865, at the end of the American Civil War, women in the Confederate states were called upon to “preserve all their chamber lye” as a last-ditch attempt to replenish rebel ammunition.

5. In ancient Egypt, urine could reveal pregnancy—and the sex of the potential child.

The Clearblue pregnancy test kit measured levels of human chorionic gonadotrophin (HCG) in the urine. The urine sampler, which looked like a plastic pen, was held in the urine stream. It was then placed in three separate chemical pots for 10 minutes each to react to the HCG. The sampler turned blue if the woman was pregnant. Science Museum, London; Wellcome Collection // CC BY 4.0

The first known DIY pregnancy test is described in the Berlin Papyrus from 1350 BCE. “Wheat and spelt: let the woman water them daily with her urine like dates and like sh’at seeds in two bags. If they both grow, she will bear; if the wheat grows, it will be a boy; if the spelt grows, it will be a girl. If neither grows, she will not bear,” it advises, according to one translation. Modern scientists put this to the test in 1963 and found that it correctly identified 70 percent of the pregnancies in the study [PDF]. When the grains were watered with the urine of non-pregnant women or men, no germination occurred. Perhaps surprisingly, it took until 1971 for the first at-home pregnancy test to reach the market.

6. An alchemist accidentally discovered phosphorus in stale urine.

In 1669, a Hamburg physician named Henning Brandt mixed up a batch of sand, charcoal, and distilled, putrefied urine, hoping to concoct the “philosopher’s stone”—supposedly a compound that could turn metal into gold. Instead, he got a soapy substance that glowed in the dark, which he called “cold fire.” Later, it was renamed phosphorus, Latin for “light bringer.” Brandt kept his discovery a secret.

About a decade later, the famous English chemist Robert Boyle devised an efficient method to extract purer, more solid phosphorus from urine (Brandt’s method had yielded only 120 grams from a whopping 5500 liters of urine). Boyle’s assistant Ambrose Godfrey took their study a step further and began extracting it from the feces of animals. Godfrey could not be described as squeamish: He made phosphorus from the excrement of horses, cows, sheep, cats, dogs, lions, tigers, bears, mice, rats, chickens, and fish.

Another 17th-century chemist, in extracting phosphorus from urine, discovered that “if the Privy Parts be therewith rubb’d, they will be inflamed and burning for a good while after.” One wonders what made him try that.

7. Urine is a chief ingredient in a seasonal Chinese delicacy.

Residents of Dongyang, China, swear by a seasonal cuisine dubbed Virgin Boy Eggs. In spring, dozens of egg vendors across the city collect the urine of boys younger than 10, to be used as a broth for marinating and cooking eggs. Vendors boil eggs in the liquid, crack the shells, and then return the eggs to the urine to simmer for whole day. Vendors keep adding fresh urine to prevent overheating, and may add some herbs and spices. The finished products have green yolks and pale golden whites. The benefits, according to the locals, include improved blood circulation, protection against heat strokes, and reinvigoration.

8. The world’s first dose of penicillin was extracted from urine.

Thousands of glass fermentation vessels like this one were used in Glaxo (now GlaxoSmithKline) laboratories in the late 1930s and early 1940s to produce penicillin. The penicillium mold was grown on the surface of a liquid filled with all the nutrients it needed.Science Museum, London; Wellcome Collection // CC BY 4.0

On March 12, 1942, Anne Miller—a 33-year-old patient with septicemia at Yale-New Haven Hospital—became the first person to be treated with penicillin. The newly discovered antibiotic was not yet approved in the U.S., and producing it was a very slow process. In Miller’s case, her urine came to the rescue.

Because 40 to 99 percent of penicillin is excreted unchanged in urine [PDF], Miller’s doctors decided to skip the process of trying to synthesize it from scratch. An intern collected all of Millers’s waste and sent it to Merck & Co for penicillin extraction. After Miller fully recovered, scientists continued to harvest patients’ urine this way until the drug could be produced on an industrial scale.

9. Astronauts recycle their urine into drinking water.

Normal human urine is about 95 percent water and presents a very appealing target for recycling—especially where potable water is scarce, like the International Space Station. On the ISS, the American crew derives its drinking water supply by recycling urine (and condensate from air). Astronauts pass their urine through a Water Recovery System (WRS) that consists of a Urine Processor Assembly (UPA) and Water Processor Assembly (WPA) [PDF], which produces about 3.6 gallons of water per day. The Russian crew doesn’t recycle their urine, though—they collect it in bags and send them over to the American side, where it's added to the supply for recycling.

Even on Earth, recycling urine into potable water is gaining traction. Belgian scientists have developed [PDF] a machine that uses a solar-powered boiler and a special membrane to produce potable water from urine.