Some 47 ingots of 'orichalcum' have so far been recovered from the ancient underwater find.

Described as brass-like and made through the reaction of zinc ore, charcoal, and copper, the alloy has never before been discovered in such quantity. Uncovered back in 2015, the ingots' composition was revealed only after analysis using X-ray fluorescence, reported Seeker.

Two Corinthian helmets, believed to have been part of the ship's defense against pirates, were also discovered at the shipwreck. "Another hypothesis is that they were meant to be an offer to the gods," according to Sebastiano Tusa, an archaeologist involved in the find and superintendent of the Sea at Palermo.

Orichalcum became legendary through the writings of a Greek philosopher Plato, who wrote that the material was mined in Atlantis, where it covered Poseidon's temple.

Along with the ingots 39, lumps of orichalcum were also recovered from the shipwreck, believed to have sunk en route from Greece to Gela in Sicily, a wealthy city, rich in artisan workshops.

"It was likely caught in a sudden storm and sank just when it was about to enter the port," Tusa said.