Divers pulled a lump of corroded bronze from a Greek wreck in 1901. X-ray scans later revealed dozens of gears built to predict eclipses and planetary positions.

Nothing of comparable complexity shows up again for more than a thousand years. Researchers are still arguing about how many planets the front dial displayed and who built it.

Why it is in the vault: it is the kind of find worth coming back to. Add sources, corrections and related links in the discussion thread.