I.e.: they don’t carry high power microscopes because apparently there’s no room for one on a 900kg rover the size of a car.
A good enough microscope can easily tell the difference between life and non-life, especially in the presence of water. If it moves on its own, it is almost certainly alive!
Certain kinds of chromatographs can conclusively determine that no complex chemicals are present, the kind essential to life. I.e.: if only simple metal oxides and the like are present, then you have only a rock.
They are still arguing over this one three decades later: https://en.wikipedia.org/wiki/Allan_Hills_84001
https://www.science.org/doi/10.1126/science.abg7905
" Inorganic precipitation processes are capable of producing a wide range of morphological outputs. This range includes shapes with both crystallographic and non-crystallographic symmetry elements. Among the latter, morphologies that mimic primitive living organisms are easily obtained under different physico-chemical conditions including those that are geochemically plausible. The application of this information to the problem of deciphering primitive life on the early Earth and Mars is discussed. It is concluded that morphology cannot be used unambiguously as a tool for primitive life detection. "
https://www.spiedigitallibrary.org/conference-proceedings-of...