The prototype has been nicknamed the Twiggy Macintosh because it features the same 5.25-inch double-sided floppy disk drive originally created for the Apple Lisa, which had been codenamed the Twiggy during its development. Those drives were notoriously unreliable, and since the Macintosh didn’t come with any internal storage, a disk drive users could rely on was a critical component.

Apple eventually opted to use a new 3.5-inch disk drive design from Sony, and Steve Jobs reportedly ordered all of the Macintosh Twiggy prototypes to be destroyed — but not all of them were.

This specific Twiggy Macintosh originally came from the developers of the word processor MacWrite and was one of two prototypes restored to working order in 2014. Less than five are known to exist, but what makes this prototype especially collectible is that it features model number #M0001 on the underside, making it one of the earliest.

Other lots available through the Bonhams History of Science and Technology auction, which runs from October 13th to the 23rd, include a specimen of original penicillin mold in a medallion inscribed by Alexander Fleming and a Blue Box device from 1972, based on a design by Steve Wozniak, that could be used to hack telephone systems.