Perhaps someone used a future copy of Gray’s Sports Almanac to score some easy money: An anonymous bidder plunked down more than half a million bucks for Marty McFly’s hoverboard. 

The prop from 1989’s Back to the Future 2, which was autographed by Michael J. Fox and his onscreen nemesis, Thomas F. Wilson, aka Biff Tannen, sold for $506,250 as part of U.K.-based PropStore’s most recent Hollywood memorabilia auction.

The auction house’s event raised nearly $8 million total, thanks to buyers spending big on items including Tom Hanks‘ volleyball pal, Wilson, from 2000’s Castaway, a full-sized Terminator endoskeleton, and more. 

“Wilson” was the second-highest-earner of the event last week, fetching more than $388,000 including premiums and fees, while a light-up X-wing miniature used in 1983’s Return of the Jedi came in third, selling for more than $320,600 when the hammer fell.

Tying for fourth place were a helmet worn by Russell Crowe‘s Maximus in the 2000 Oscar-winning epic Gladiator, and Hayden Christensen‘s Anakin Skywalker lightsaber from 2005’s Star Wars: Revenge of the Sith, both of which sold for $303,750. 

Rounding out the top five biggest earners was Will Ferrell‘s Buddy the Elf costume from 2003’s Elf, which scored $295,312.