It is quite possible that a thing as complex as life has some qualities that could yet surprise us and redefine our understanding. What we try to consider is life similar to the one on Earth and even with the NASA’s definition there could be different types of systems and organisms, based on different chemistry, or adhering to separate set of rules. Viruses are an interesting example of microbes that are considered to be not-living, yet they are certainly not the same as non-living matter, such as rock