Nanobacteria as Missing Link in Origin of Life
There's been little research on nanobacteria because they do not meet all criteria of life, but this should be all the more reason to research them, to find out how life is different from death. As living matter arose from dead matter and has no contradistinction from it (Oparin), nanobacteria may form an intermediary between the two. Nanobacteria could've contained some of the earliest genes, isolating each variation when replicating until some became more viable than others, which could've given them enough time to mutate at random until they mutated to non-random. If nothing else, nanobacteria could teach us how to create our own self-replicating nanoparticles, and should therefore be a priority in research.