Here is some more evidence from the journal Geology that microbial life may exist or once have existed on Mars.

Depletion of phosphorus, vesicular structure, and replacive gypsic horizons of these Martian paleosols are features of habitable microbial earth soils on Earth, and encourage further search for definitive evidence of early life on Mars.

I’m interested in the question of whether life on Earth is truly alone in the universe. If we find just one bacterial cell on another planet, and as long as we don’t think that cell came from Earth or is an ancestor of life on Earth, the question will have been answered. If we can find life just one other place, then it will be likely that there is life all over the place.