It was a dark summer night, and Harley Eaton and Connor Rudolph were bored.

The two friends and self-described military collectors were passing time at Rudolph's house, an old property out in California's sun-scorched Mojave Desert on a Monday evening earlier this month, when they remembered that one of them had a metal detector in their car. It was unlikely they'd find anything, they thought, especially in the arid region near Palm Springs where they lived.

But they picked up their tools anyway, and began wandering along a barren-looking trail. At first, they didn't find anything out of the ordinary, just the usual array of loose screws and cans. Then, they heard a resounding beep. And it kept getting louder.

They pulled out their pickaxes and started digging.

Slowly, they began to unearth a corroded metal box resembling a small casket. When they flipped it open, they saw two crimson runes emblazoned on the side that resembled one of the Nazi Party's most infamous symbols: two stark S's that look like a pair of lightning bolts. Commonly used in white supremacist groups, the runes are derived from Schutzstaffel, a paramilitary organization that operated under Adolf Hitler and thought of itself as the "racial elite."

"Oh my god," one of the two friends could be heard saying in a video as they pulled the chest out of the ground. Inside, it was full of dirt, along with some artificial flowers tied to a nail. To date, they still don't know what it is, exactly, or who it once belonged to. Neither do experts.

"At first we thought it was a pipe, maybe a water line or something," Eaton told SFGATE. "We just kept digging until we could open the chest, and we opened it, we saw the big SS symbol, and we freaked out."

For Eaton, 19, and Rudolph, 20, this was a shocking discovery, even for avid collectors. Gathering anything from World War II-era helmets to deactivated grenades, they've also recovered musket bullets near Apple Valley, a region where U.S. troops were known to be present around the time of the Civil War. Rudolph, who doesn't know much about the history of his property except for the fact that it was built in 1956, said he found an unmarked grave nearby that he suspects dates back much earlier.

Keith Darcey, a spokesperson for the the National WWII Museum in New Orleans, shared photos of the chest with the museum's curatorial team, but said there wasn't enough information to tell what it is or whether it's authentic. Similarly, AJ Solovy, a PhD candidate and historian of modern Europe at UC Berkeley, told SFGATE that they can't say whether it's an authentic artifact or the runes were painted on later.

"Either possibility seems plausible," they wrote.

The location of the chest, and color of the symbols, has also shed some doubt on the origins of the object.

"I can't find any definitive explanation for why the chest would have been buried there or why it has the 'SS' on it," Chris Rodda, the Military Religious Freedom Foundation's research director, told SFGATE. "I've also never seen a red 'SS' symbol in any context, so that's odd."

Solovy said that in order to know the object's true history, it would likely need to be taken to an antiques dealer. More would need to be known about the history of the property, too. For now, though, Eaton knows exactly what they'll do with the trunk: