An asteroid trailing after Mars could actually be the stolen twin of our moon. The asteroid in question, called (101429) 1998 VF31, is part of a group of trojan asteroids sharing the orbit of Mars.
Trojans are celestial bodies that fall into gravitationally balanced regions of space in the vicinity of other planets, located 60 degrees in front of and behind the planet.
Most of the trojan asteroids we know about share Jupiter’s orbit, but other planets have them too, including Mars and Earth too.