Petroglyphs are valuable relics of a past age – rock carvings that are produced by chiseling directly into a rock’s surface. That being said, archaeologists and conservationists alike are dismayed when these carvings are defaced by graffiti. What is the best way to clean up the mess? The answer surprisingly is a product named “elephant snot.”

For petroglyphs found outside Albuquerque, New Mexico, conservation officials are turning to the strange product to prevent damage from the vandalism, reports KOB Eyewitness News 4.

“All of the petroglyph areas are ecologically sensitive, so when we look at trying to do any kind of graffiti repair, we have to be very cautious,” said Matt Schmader, the Albuquerque Open Spaces director.

These rare carvings can only withstand low-impact cleaning. Sand blasting or using harsh chemical substances are prohibited by law. Enter elephant snot.

Contrary to its name, the substance does not come from elephants, but is instead a biodegradable, environmentally safe product, according to Schmader. The material costs $75 per gallon.

To remove recent vandalism, the city’s Parks and Recreation Department just needed to buy one gallon of the substance.