When lightning strikes sandy soil, the soil melts into a glassy stone called a fulgurite. These stones can appear branch-or rootlike, almost as if the bolt of lightning has been fossilized or petrified somehow. The glassy material in the fulgurite is known as lechatelierite, a substance that can also be formed by meteors striking the ground. One of the largest fulgurites ever found is housed at Yale University’s Peabody Museum of Natural History and is about 13 feet (4 meters) in length.