In the spring of 1901, sponge divers working off the Greek island of Antikythera brought up something nobody could explain.
This is the shipwreck, right? A cargo ship that went down in the first century BC, loaded with bronze statues and glassware.
That's the one. And among the treasures was a corroded lump of bronze and wood, about the size of a shoebox. The next year, an archaeologist noticed a gear wheel in it.
A gear wheel. Two thousand years old.
Today it survives as eighty-two fragments in the National Archaeological Museum in Athens, with at least thirty bronze gears.
So what did it actually do?
You turned a handle, and the dials showed where the sun and the moon were, the phase of the moon, and when the next eclipses would come.
And the moon even sped up and slowed down, the way it really does in the sky. That came from a pin riding in a slot between two gears.
X-ray scans in 2005 revealed thousands of tiny letters engraved on it, a user's guide of sorts. There's even a dial for the athletic games, the Olympics among them.
And nothing that intricate turns up again for more than a thousand years.
Which is why it's often called the first analog computer.