A barnacle-covered lump pulled from a Roman shipwreck sat in a museum for two years before anyone noticed it was a 2,000-year-old computer that could predict eclipses.
In 1901, Greek sponge divers discovered a Roman cargo ship off the island of Antikythera at 45 meters depth. Among the artifacts hauled up was what appeared to be a corroded bronze lump. It sat in a museum for two years before archaeologist Valerios Stais noticed it contained an embedded gear.
The device turned out to be a hand-cranked mechanical computer with at least 30 interlocking bronze gears. It could calculate and predict astronomical positions, lunar phases, and eclipses decades in advance — the oldest known analog computer by more than a thousand years.
Dating to approximately the 2nd century BC, its engineering sophistication wasn't matched until 14th-century European astronomical clocks — a gap of over 1,400 years. For most of that time, no one even knew the technology had ever existed.
The mechanism tracked multiple astronomical cycles simultaneously, including the Metonic cycle and the Saros cycle for predicting eclipses, the phases of the moon, and the four-year cycle of the ancient Greek Olympic Games. Its inscriptions served as a manual for its operation.
Modern researchers used X-ray tomography to read hidden inscriptions inside the corroded fragments. These suggest the device may also have tracked the movements of all five known planets — effectively a hand-held model of the observable solar system.
The ship carrying it was Roman, but the device itself was almost certainly made in the Greek world — possibly Rhodes or Corinth. The craftsmen who built it left no successors. Whatever workshop tradition produced the Antikythera Mechanism vanished completely, and nothing like it was made again for over a millennium.