A grain of sand buried for an extended period of time in earthworks or on the bottom of the ocean, accumulate a luminescence signal. Scientists use this signal to determine how long a particular grain of sand has been buried. With a new, highly sensitive camera, they can photograph these signals with pinpoint accuracy. In fact, they are even trying to determine where the grain of sand comes from and how it has spread across the ocean floor.
Click here for original story, Light reveals the origin of a grain of sand
Source: Phys.org