A characteristic piece of natural glass. Tektites are found distributed on the Earth’s surface in four main areas, called strewn fields, which are in Australasia, the Ivory Coast, Moravia and Bohemia in the Czech Republic and Texas and Georgia in the USA. Individual tektites range up to 15 kilograms in mass though most are much smaller and their shape and structure suggest that the molten material from which they formed underwent a high-velocity flight through the atmosphere. The most popular theory for their origin is that they were created from terrestrial material when the impacts of large meteorites melted and ejected rock at the impact sites. Their ages and links to known impact structures support this theory.