Meteorites offer glimpses of the earliest stages of planetary formation. Stony-iron meterorites come in two main classes: pallasites and mesosiderites, and it was previously thought they may have had similar origins. A new study, however, has revealed that their oxygen isotope properties differ and that they come from distinct places. Accordingly, the characteristics of mesosiderites suggest they came from the third largest asteroid, Vesta, which is the target of the NASA Dawn Mission. On the other hand, pallasites are made of mixed core-mantle material from a disrupted asteroid, indicating that extensive asteroid deformation was an integral part of planetary enlargement in the early solar system.