Submitted as evidence: the enigmatic bronze device known as the Antikythera Mechanism. It doesn’t look like much – a few badly corroded lumps, nearly unrecognizable after two thousand years in Davy Jones’ locker. The mechanism was discovered by Greek sponge divers in 1901, part of the wreckage of a Roman cargo ship sitting under 45 meters of water off the island of Antikythera, in the Aegean Sea. For decades nobody paid much attention to it. This despite the fact that as early as 1902, a Greek archaeologist (Valerios Stais) noticed that there were what looked like gears inside the lumps of bronze pulled from the seafloor… More here.
It feels like we should all know more about this, but I was not aware of its existence at all.