There is a study called "Deep Carbon Observatory" and scientists from that study found billions of bacterias underneath our feet and they dug very deep, even under an ocean and sea. There could be way more life inside the earth than it is on the earth and that means Mars could be thriving in bacterias too. Also, fun thing is that if every animal on this planet goes extinct, after some millions of years the old bacteria will rise to the surface and it would be the new life of earth that will most likely have a long evolutionary process. Maybe that's how we came to be after dinosaurs?
