Think that butter in the back of your fridge is old? Last week, a man harvesting peat in Ireland’s Meath County unearthed a massive lump of 2000-year-old “bog butter.” It weighs around 22 pounds and smells like a strong cheese, the Belfast Telegraph writes. And yes, it’s still edible after all these years (although we wouldn’t recommend tasting it).

Experts think that prehistoric people buried butter to preserve it, or as an offering to the gods. They often placed the topping in a wooden casket, or wrapped it in an animal hide, before placing it underground. This particular ball of butter was buried without a cover, 12 feet underneath the bog's surface. The nature of its burial suggests that it wasn’t meant to be dug up.

Andy Halpin, who works in the National Museum of Ireland's Irish Antiquities Division, says that the butter was significant because of its burial place. It was found near the town of Drakerath, where, long ago, 11 townlands and the boundaries of three ancient baronies converged. “These bogs in those times were inaccessible, mysterious places," Halpin said. “It is at the juncture of three separate kingdoms, and politically it was like a no-man's-land, that is where it all hangs together."

Bog butter might seem bizarre, but it’s hardly rare. Over the years, archaeologists have found hundreds of butter caches in bogs across Northern Europe, some of them dating all the way back to the Middle Iron Age (400-350 BCE). Last week’s find will be given to the National Museum of Ireland, where it will be carbon-dated and preserved.

Bogs are acidic environments with very little oxygen, so artifacts, animals, and people buried in their depths can remain well-preserved for thousands of years. Over time, people have unearthed many ancient artifacts from Europe's peat bogs: golden treasures, human bodies, and even a 1200-year-old book of psalms.

[h/t Belfast Telegraph]