8 gram Moldavite specimen, approximately 5cmx1cm.
Moldavite is a glassy substance believed to have been formed approximately 15 million years ago, as a result of the Nördlinger Ries meteorite impact in Bavaria, Germany.
As the meteorite impacted the Earth, huge quantities of dirt/rock were instantly melted/ejected from the newly forming crater, hurled dozens to hundreds of miles downrange, or into low Earth orbit.
As the molten droplets cooled while re-entering the upper atmosphere, the drag forces produced regmaglypt like features, similar to those found on meteorites.
Since Moldavite originated on Earth, and was ejected by a meteorite impact, but later returned to Earth, it belongs to a class of objects known as "Tektites".
via Flickr http://flic.kr/p/nyhBsw