Almost 500 million years ago in the Ordovician Period, two large bodies in the asteroid belt collided. Two asteroids, or an asteroid and a comet, blew apart and their debris and dust fell to Earth. One of these large bodies was the source of all the L-chondrite meteorites that have frequently fallen to Earth since. And the one that destroyed it? Until now, a remnant of that killer space rock has never been found. But LiveScience reports that scientists have found a strange meteorite in a Swedish limestone quarry that may be the missing "other half," the study detailing its discovery claims. For now, scientists have aptly named the rock "mysterious object." And what’s so mysterious about it? Firstly, all of the previous 100 fossil meteorites found in the quarry have been of the L-chondrite variety. This new rock is part of a group called achondrites, but its texture and exposure age make it very different.
Exposure age—how long it flew through space—is integral to placing the "mysterious object" at the scene of that epic space crash, LiveScience explains. Scientists found that it whizzed from the asteroid belt to Earth in a million years, which is about how long it took L-chondrites to get to the same quarry. That indicates the two groups of meteorites sailed in the same hunk of debris. "One thing our study shows is that we maybe don't know as much as we think we know about the solar system," says the study’s lead author. He will now begin a global search for evidence of other similar achondrites; the search and further studies may help scientists understand the history of the asteroid belt and solar system. (The moon recently had its own run-in with an asteroid.)