To peer into Earth's deep time, meet a hardy mineral known as the Time Lord

Zircons studied by the research team, photographed using cathodoluminescence, a technique that allowed the team to visualize the interiors of the crystals using a specialized scanning electron microscope. Dark circles on the zircons are the cavities left by the laser that was used to analyze the age and chemistry of the zircons. (Michael Ackerson/Smithsonian)

The oldest known Earth stuff that remains on the surface of our planet is a mineral that's been called the "Time Lord" because it's so incredibly good at keeping geologic time.

The mineral is zircon, and scientists have found bits of it that formed 4.37 billion years ago, not too long after the proto-Earth's epic collision with a Mars-sized object that spawned our moon.