We found all of the craters are on continents that were close ... Some scientists have even suggested that Phobos and Deimos, the small moons of Mars, may be remnants of an ancient ring.

The study's findings have implications for Deimos, too. Fornasier noted that ... That includes the 9-kilometer-wide (5.6-mile-wide) Stickney crater, Phobos' largest landmark.