Mars trojan

One theory suggests that they were primordial objects left over from the formation of Mars that were captured in its Lagrangian points as the Solar System was forming.

[1][2] Another explanation involves asteroids chaotically wandering into the Mars Lagrangian points later in the Solar System's formation.

[5] Since olivine-rich objects are rare in the asteroid belt it has been suggested that some of the Mars trojans are captured debris from a large orbit-altering impact on Mars when it encountered a planetary embryo.

[6][3] Presently, this group contains 17 asteroids confirmed to be stable Mars trojans by long-term numerical simulations but only nine of them are accepted by the Minor Planet Center.

[7][3][4][8][9][10][11] Due to close orbital similarities, most of the smaller members of the L5 group are hypothesized to be fragments of Eureka that were detached after it was spun up by the YORP effect (Eureka's rotational period is 2.69 h).