A missing piece of the world’s oldest analogue computer, the Antikythera Mechanism, is believed to have been found on an Aegean seabed.

Discovered in 2017 resembling greenish rock, further investigation on land has revealed it to be a bronze eight centimetre disk. It features four metal arms at each corner with holes for pins, an x-ray revealing the engraving of Taurus the bull.

While it cannot be said conclusively whether it is a missing part of the Mechanism or not, based on evidence found so far, it is said to look exactly like other parts of the computer.

The other possibility is that it could be part of a second mechanism that has yet to be unearthed, or something else entirely.

What is known so far is that Antikythera Mechanism was built by the ancient Greeks to calculate different astronomical positions.

It first disappeared 2,200 years ago after the ship carrying it sunk near the island of Antikythera. It was first rediscovered in 1901 by sponge divers, who took their intriguing find back to land, where it was investigated by archaeologist Valerios Stais at the National Archaeological Museum in Athens.

Since then scientists have found that the computer can perform basic mathematical functions and can accurately track the movements of the sun, moon, planets and constellations, along with the timing of equinoxes and eclipses.

The site of the discovery has since been both explored and looted thoroughly. Among the finds have been statues made of bronze and marble, coins, a sarcophagus lid, along with furniture.

Aside from the importance of the Mechanism itself, Sarah Bond, an associated professor of Classics at the University of Iowa, says its discovery is significant when it comes to the field of archaeology as a whole.

“The Antikythera Mechanism is an important object in the historical record of ancient technology, but is also a prism for tracking the development of archaeology as a professional field,” she said.

“It reveals the advanced astrological instruments created and used by ancient engineers, but the protracted nature of the undersea dig reveals archaeological advances in scanning, 3D modelling, and many other sophisticated approaches in reconstructing and analysing the computer.”

Examinations on the bronze disk continue.