Episode 11 of Fox's Cosmos, "The Immortals", focuses things that stand the test of time - the first written word, stories, and organisms that can survive for millenia. All these things stand the test of time - and could possibly have extraterrestrial origins.
Early in the formation of our solar system, Earth and the other planet were slammed by asteroids and other rocks. Rocks were flying all over the place, and organisms were along for the ride - possibly exchanging life between the planets.
Check out some video from the show below, as well as the Storify of the latest live tweet below!