Here I'm going to posit something I've been thinking about for some time,
namely the red color of Martian soil. I'm thinking that since life
was able to start so early on Earth, almost immediately following
The Hadian, such that it would have been possible that cyanobacteria
could have spawned a Martian oxygenation event that could
have given rise to the red planets color.
It makes sense to me that life, if it came to Mars, would have
started there firsr. I believe that because it is smaller than Earth
it's 'Hadian" period would have ended sooner, lending to an
early start for quick forming life, in an envionment alien to
us now. The planetary "mechanics" would also be very different
with oceans being heated by the warm Martian crust rather
than by solar heat, for some time. Once cyanobacteria arrived
it would persevere longer as competition form higher organisms
would be without time to evolve.