Scientists using two different age-determining techniques have shown that a tiny zircon crystal found on a sheep ranch in western Australia is the oldest known piece of our planet, dating to 4.4 billion years ago. Researchers say the discovery indicates that Earth's crust formed relatively soon after the planet formed and that the little gem was a remnant of it. "Zircons can be large and very pretty. But the ones we work on are small and not especially attractive except to a geologist," a researcher said. "If you held it in the palm of your hand, if you have good eyesight you could see it without a magnifying glass."