Giant ants?.................
Rocks?
Bees.
There was an earlier high tech civilization on Earth that got wiped out by a series of naturally occurring large impacts hundreds of millions of years ago. Prior to the cataclysm, the Moon began as a sort of landfill for trash, rubbish, waste, and "recycling" that the lost civilization had to get rid of. It started out in various smaller piles, which became a hazard to space travel, so a cleanup effort began which gathered the small piles into a single large one, which got larger and larger, then had to be moved away from the Earth's surface. Slowly but surely it got to the size we see today. ;^)
But the whole "lost civilization on Mars" thing, now that's actual rubbish.