I wonder if Venus had a moon that spiraled inward and crashed down as well. Maybe that’s why it has an unusual retrograde rotation (or maybe the impact that created the moon caused that, and it then helped slow down the moon until it crashed). Not that we would be able to find out for sure, given Venus’s multiple volcanic resurfacings.
In any case, it would be pretty cool to find out that Mars had a much larger moon at one point, even if only for a few million years. Another similarity between the Earth and Mars.