Much like negligent dog owners who don’t clean up after their pets, America’s astronauts have been known to leave doody in some crazy places.

The legendary Apollo program is one of mankind’s greatest achievements. In addition to successfully transporting 12 astronauts to the moon between 1969 and 1972, it enabled them to bring back over 800 pounds of dust, rocks, and other samples.

But, as you probably already know, space was pretty limited on the command modules. So now did the astronauts free up some room for all of those samples? Well, they left a few things they brought with them behind on the moon’s surface.

In addition to ditching gear and supplies they no longer needed, the astronauts placed symbolic objects like American flags and a gold plated telescope on the moon. That’s not everything. There are an estimated 96 bags filled with the vomit, urine, and feces of Apollo astronauts.

Naturally, this isn’t a topic that’s widely discussed in your average high school history or science class. In case you were wondering, astronauts on these missions used what’s called a “Fecal Collection Receptacle Assembly” when they had to go poop. What’s that, you ask? A plastic bag that they taped to their bottoms so none of their excrement would escape and float around the modules in zero gravity.

A more sophisticated setup called the “Urine Transfer System” was used on at least a few of the missions. It consisted of a condom-esque tube linked to a metal apparatus that could be connected to a bag or a pressure valve. That latter was attached to the module’s walls for those astronauts who preferred to, essentially, pee directly into outer space. Needless to say, using the bag was the safer of the two options.

Astrobiologists are curious to learn more about all of that biological waste still sitting on the moon. Given the conditions on the lunar surface (the temperature up there can dramatically range from -387 Fahrenheit at night to 253 Fahrenheit during the day), they theorize that the poop may have undergone weird, genetic mutations over the past 40-plus years.