A thrift store in Pennsylvania stumbled upon an exceptionally rare find amidst a donation, turning it into a significant windfall.

In Dubois, Pennsylvania, a Goodwill store was gifted a box of miscellaneous jewelry that harbored an unusual item: a gold mask from LEGO’s Bionicle series, a popular line of action figures from the early 2000s.

The discovery initially puzzled the staff. “It was mixed in with a box of assorted jewelry that came from our State College location. It had been sorted through once before it got to us,” shared a Goodwill representative from North Central Pennsylvania during a conversation with WTAJ, a local news outlet.

Unlike the standard plastic material of most LEGO pieces, this particular Bionicle mask, known as the Kanohi Hau, was made of 14-karat gold. It was part of an extremely limited edition series produced by LEGO, with only 30 ever made. “There were 25 distributed through special promotions, and the remaining five were kept by LEGO employees,” explained Chad Smith, a Goodwill executive in North Central Pennsylvania, in a CBS News interview. “To see one resurface after 23 years is quite extraordinary.”

The auction for this 1-inch-tall gold LEGO mask began at $3,300. Following intense interest and 48 bids, it eventually sold for an impressive $18,101.

To illustrate the rarity and value of this piece, consider that one of LEGO’s priciest standard sets, the Star Wars Millennium Falcon, which consists of over 7,500 pieces, sells for $850. Another massive set, the LEGO Titanic, stretches over four-and-a-half feet in length and is priced at $680, making the sale of the gold mask for over $18,000 all the more remarkable.