The Antigotera Clock

There's this thing called the Antigotera device, which I certainly know. It did things like show you how various celestial events as well as things like differential gearing or it didn't show up again for 1500 years. We had to reconstruct with X-rays, took us a really long time to figure out how it even worked. And there's a lot of technologies that we take for granted but you don't necessarily need them to do stuff. They just evaporate and you don't realize they're gone.