Call it an auction-room ace. A gilded bronze censer from the 17th century has sold at the Switzerland-based Koller Auctions for a stunning $4.9 million, 6,082 percent above its high estimate of $79,260. For years, the family who owned it had used it to store tennis balls. (What, you don’t keep your sporting equipment in multi-million dollar treasures?)

The family long thought the object was a 19th-century copy and only realized its true value when they invited an auction-house specialist over to view other works in their collection. The specialist, Regi Preiswerk, quickly spotted the item and recognized it for what it was: an incense burner believed to have been designed specifically for a Chinese emperor some 300 years ago. The object features intricately carved peonies and a golden phoenix head on each side, with their scaled torsos serving as handles.

According to the auction house, the piece has remained within the same German, Swiss-based family for about 100 years, since an ancestor acquired it on a trip to China. At the sale earlier this month, a reported 30 people vied for the work, which Koller described as a “one-of-a-kind object” and which carried an estimate of €43,860 to €70,180 ($49,534 to $79,260).

The “Phoenix and Peony” Bronze Censer. Courtesy of Koller Auctions.

The family had reason to believe the work was more tchotchke than a trophy. In the 1960s, they offered it to a Berlin museum, who turned down the generous donation. They later showed photographs of the piece to a British auction house, which chalked it up as a 19th-century reproduction.

After being rebuffed by supposed “experts,” the family went on with their lives, storing extra tennis balls and other knickknacks in the punchbowl-sized piece. “After all that [the family] thought it wasn’t worth a lot, but they liked it. They displayed it. As you do with a bowl in your house, they put things in it, and they put tennis balls in it,” Karl Green of Koller Auctions told CNN.

Ahead of the sale, the Swiss auction house exhibited the work in Hong Kong. The auction kicked off on June 4 with more than 30 people frantically calling in and placing bids in the salesroom.

An auction-house representative said that naturally, the family was thrilled as they watched the action online, telling Metro UK, “I’m not sure if they had a tennis court at home, but I think they could afford to put one in now.”