Mysterious jars of pickles have been appearing on a Missouri highway on-ramp over the last six years, and no one can quite figure out why.

According to Fox 2, the pickles were first spotted around 2012, propped up on the on-ramp of I-270 near Des Peres, Missouri, and they've been coming and going ever since. The pickles have come and gone throughout the years, sometimes disappearing from the highway for as long as a year. It's not the same jar—sometimes its a jar of whole pickles, sometimes kosher spears—but whenever one jar disappears, another eventually comes along to its place.

The great pickle mystery has apparently captured the imaginations of Des Peres community members, highway commuters, and pickle enthusiasts alike, and a Facebook group has been dedicated to how—and why—the pickles keep finding their way to that particular stretch of road.

"These Pickles need a Fan Page," the page description reads. "They have sat on the divide barrier on the exit ramp from 270 North at Manchester for years, if I had to guess mid to late 2012. They have survived snowmageddon, construction, and protesters. There has got to be a story behind these pickles and inquiring minds want to know."

And even though the page has been active since 2014, there are still more questions than there are answers. The truth, like a particularly stubborn pickle jar, has been tough to crack.

Who is the mysterious person—or persons—keeping the northbound I-270 on-ramp flush with pickles? Is it some sort of Vlasic viral marketing stunt, or just a Good Samaritan trying to offer drivers a quick snack for the road? Are there ever any bread and butter pickles, or are they strictly dill? More importantly, does anyone actually like bread and butter pickles?

As long as the pickles keep appearing, the intrepid Des Peres detectives will be trying to get to the bottom of the mystery—and the brine will likely continue to flow on I-270 until they do.