If that's true, the rock is "still extremely interesting," says Tim McCoy, who curates the Smithsonian Museum of Natural History's collection of 35,000 meteorites. "[It] tells us something about the birth of the solar system, but not the birth of the innermost planet."

The olive green meteorite, flecked with bits of white and brown, first came to scientists' attention last year when a German collector, Stefan Ralew, saw the unusual stone in Morocco and shipped it off for analysis to Tony Irving, a geochemist and meteorite specialist affiliated with the University of Washington in Seattle. Irving routinely receives such packages from all over the world.

"From experience, I knew it was very unlikely to be an Earth rock," Irving says. "It wasn't from Mars, and if it was a meteorite, it was highly unusual." As it turns out, the rock was even weirder than it looked.