Life on mars? It seems the last clutches of life may reside in pools of brine (salt water) on the surface, and even in smaller puddles hidden in the shadows of large boulders. This article about the Mars 2020 mission explains a lot why the site was chosen. As you can tell from the pictures of the Jezero crater area, this was once part of a huge river delta, and I think any can see visually, just how much water once flowed. As they are searching for simple organic compounds, I think they will find some much larger fossils than was expected.
Life may even still be inside the planet in the form of ancient lava tubes, and those and examples of their openings to such as the Povonis Mons volcano could be instant habitats for protection from solar rays and meteoroid impacts. Here is an article from Inverse that covers the topic in some detail, also. Many jumping off points link wise to keep you busy researching. We may even find geothermal power options and water resources inside an ancient but still warm volcano. This great write up about the seismic activity, magnetic fields (Space.com) and such and also solidly addressed again in this great article, “There’s a lot more happening on Mars then we knew” (via Gizmodo).
With all the huge amounts of data we have on Mars, it this point we know there were once huge oceans. (NASA) I think there may have been a lot more water than ‘primitive oceans‘. (wiki) We can see the remains of beaches and river deltas and the mineralogy. The question is What Happened to the Water? Many theories abound but I think the answer lies in Ceres. The asteroid belt between Mars and Jupiter may have once contained a planet, called Phaeton in the early phase of our solar system. Unfortunately, it was most likely in an unstable Titus-Bode orbit, and some sort of collision or gravitation tugging from Jupiter and Mars may have destroyed it, resulting in Ceres as the remains of its rocky core. Mars may have been bombarded with the remains of this event, and its 2 moons may be larger chunks that were captured over time.