Mars is far from fully explored
Finding evidence of just ONE microbe on a planet other than the Earth would be the most significant discovery man has ever made.
It would confirm that we absolutely cannot be alone in the universe.
It would confirm that life is common.
If it were a living microbe, studying and comparing it's DNA or whatever it would have in place of DNA, could prove that more than one genesis took place.
That would be the most earth shaking discovery of all time.
Hopefully the phoenix mars lander will "stumble" upon one such microbe!