You never know what you’ll find on eBay. Case in point: A volunteer with the UK’s National Museum of Computing spotted a rare machine used by the Nazis to send encrypted messages during WWII on the auction site, the Guardian reports.

Listed as a “telegram machine,” the military-issue Lorenz teleprinter was being stored in a garden shed “with rubbish all over it” in Essex, museum volunteer John Wetter tells the BBC.

The museum bought the machine for about $15. Initially, museum volunteers thought they had discovered a civilian version of the teleprinter. But later they realized it was a military-issue machine upon discovering a swastika and military serial number, according to the Telegraph.

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"Everybody knows about Enigma,” the museum’s Andy Clark tells the BBC, referring to the machine used by Nazis to send communications to frontline troops. “But the Lorenz machine was used for strategic communications.” The Lorenz also produced a more complex code than the Enigma, per the Guardian. But mathematician Bill Tutte was able to break it, leading to the creation of the first programmable computer, Colossus, that could translate messages sent via the Lorenz. “We were able to drip-feed the Russians the locations of the German tank divisions of Kursk,” Wetter tells the Telegraph, adding that it was the “turning point of the war.” On June 3, the National Museum of Computing plans to recreate the breaking of the Lorenz cipher code using the teleprinter and a Lorenz cipher unit on loan from Norway’s Armed Forces Museum. But there is still one more missing component: the electric motor, which the museum is asking the public to keep an eye out for. (This man believes a $500 million treasure is hidden in a Nazi bunker.)

This article originally appeared on Newser: Rare Nazi Coding Machine Found on eBay