Given the vast number of various species on Earth, it is logical
to assume that some of them might come from planets beyond or
within the Sol System. Mars once has liquid water that covered a
portion of its surface, but dried out over billions of years.
Traces can still be found there. What if, buried hundreds of metres
below the Martian surface is a vast city network that stretches all
across the planet? The Martian Civilisation, destroyed a billion
years ago by environmental pollution and weapons of mass
destruction, would have been buried by the dust storms that
constantly rage across the Red Planet. Unless humans or robots are
sent to DIG into the ground, no one would know for sure what lies
beneath. Another suggestion would be that humans and some other
mammals are actually Martians themselves, whose seeds have been
propelled towards its neighbour Earth to preserve the native
species of a doomed world.
