@Phil-A-Dork
The only problem with that theory is if microbes are found alive on Mars, they would not be able to attack our cells since we have had billions of years of completely different evolutionary drivers.
My question about life on Mars and anywhere else, the outer moons with the underground seas, if we actually find life there, is it based on our idea of DNA, double helix? Or could it have a completely different information coding system, maybe a triangle ladder with cross members or some such, there must be a thousand ways to store info in DNA like setups. And if we find the DNA is like Earthy DNA, maybe that would point to a common cause of life here in the solar system, a prebiotic cloud passing through the solar system seeding prebiotic life molecules over every planet and moon in the system.
So it will be exciting one way or the other.
Here is a bit on the origins of life here on Earth:
https://phys.org/news/2021-02-life-darwinian-evolution.html