Apparently, someone in that time had the knowledge and skill to build it. It was recovered from the debris of a shipwreck that was positively dated to the ancient Greek era.
It's one of the most enigmatic discoveries in history, and has baffled the scientific community for a long time now. Obviously, there's much we still don't know about the ancients and the extent of their technology.
Well we know that knowledge can be lost, see how long after the fall of the Roman empire it took for concrete to be rediscovered?
or just take a look at television for how far we’ve fallen.
>> Obviously, there’s much we still don’t know about the ancients and the extent of their technology.
Some overzealous ‘god-riddance’ managed to take much of that away.
I understand that it was the Arabs that ironically managed to document much of what they learned from the Greeks. The Christians later civilized the Barbarians and somehow managed to resurrect the techno movement the came back to life around the 17th century relying on the foundations abstracted by the Greeks. The monks of Ireland allegedly played a role in this but I forget how.