A rare Enigma machine — a German gadget that encoded secret messages during World War II — is up for auction.

The device is unique, even among Enigma machines. That's because it has a German navy-designed, three-cipher rotor (M3), and it even has a proper name: the Funkschlüssel.

The Nazis used Enigma machines before and during WWII, from 1934 through 1945, to send directives that their enemies couldn't decipher. But as the war drew to a close, the Germans began to destroy these machines to keep them out of Allied hands. [Photos: German WWII Base Discovered on Arctic Island]

Many Enigma machines that did survive were then demolished by Allied forces at the war's end, per orders from U.K. Prime Minister Sir Winston Churchill. Now, there are only about 250 WWII-era Enigma machines left.

Despite its rarity, many in the public now know about this machine because of the 2014 release of "The Imitation Game," a movie about British scientist Alan Turing's efforts to crack the Enigma machine's code. This was no easy feat; the sophisticated device could scramble letters into any one of 17,576 combinations, which did not include the words' original letters.

The three-cipher rotor of the enigma machine. (Image credit: Nate D. Sanders Auctions)In the end, Turing and his team were successful. They figured out the code, thanks to human error on the part of the Nazis, who ended each communication with "Heil Hitler." This helped the Allies deconstruct the messages and gave them an unprecedented look at Axis messages.

This particular Enigma machine is housed in its original wooden case. Its metal wheels have an engraving of the Third Reich emblem — a black eagle above a swastika. On the inside of the wooden case are instructions in German on how to clean and configure the machine.

The QWERTZ keyboard (different from today's QWERTY keyboards) on the Enigma machine lights up when used. All 26 bulbs are still on the lamp board, and only one is broken, according to Nate D. Sanders Auctions.

Bidding on the 28.5-lb. (13 kilograms) Enigma machine starts at $200,000. The auction ends at 8 p.m. EDT/5 p.m. PDT on May 30 at Nate D. Sanders Auctions.

Photos: World War II-Era Aircraft Carrier DiscoveredPhotos: Underwater Robots Help Recover WW II Plane WrecksIn Photos: WWII-Era Shipwrecks Illegally Plundered in Java SeaOriginally published on Live Science.