Who knew? This pottery jar being sold at a flea market was made about 2,000 years before the birth of Christ.

You never know what you'll find at a flea market … like a 4,000-year-old piece of pottery. That's what a guy in England discovered, though he didn't realize what he had until later, after he'd repurposed the jar as a toothbrush holder.

The pottery vessel, adorned with the painting of an antelope, caught the eye of Karl Martin while he was browsing a yard sale five years ago. He picked the jar up, along with another pot, for about $5 (4 pounds).

"I liked it straight away," Martin said in a statement from Hansons Auctioneers, where he now works and where the pottery was auctioned — selling for about $100 (80 pounds) in November.

The jar dates to the Indus Valley Harappan civilization, which thrived in the northwestern regions of South Asia during the Bronze Age, according to James Brenchley, head of antiquities at Hansons Auctioneers. The Indus, along with ancient Egypt and Mesopotamia, is one of the three cradles of civilizations in the Old World, he added.

This pottery jar seems to date to the Indus Valley civilization. (Image credit: Hansons Auctioneers)

That backstory was unbeknownst to Martin, a collector, at the time of his purchase. So who could blame him for plopping the jar in the bathroom, right? "I used it in the bathroom to store my toothpaste and toothbrush — it even ended up getting a few toothpaste marks on it," he said.

Years later, while helping Brenchley unload a van at the auction house, Martin noticed some of the pottery going up for auction looked similar to his toothbrush holder. "The painting style looked the same, and it had similar crudely painted animal figures," he said in the statement.

Brenchley examined the pot and confirmed that it was a genuine artifact from Afghanistan dating to 1900 B.C.

"That means it's around 4,000 years old — made 2,000 years before Christ was born," Martin said. "It's amazing, really. How it ended up at a South Derbyshire car-boot sale, I'll never know."

Originally published on Live Science.