PROKARYOTIC RESISTANCE TO RADIATION. “There is an enormous range in resistance to ionized radiation among modern unicellular life forms, including prokaryotes, which Sharma et al. (2017) showed to correlate with Mn2+ ions in antioxidant complexes within cells. This idea can perhaps be tested directly by analysis of cellular residues in Precambrian rocks.”
https://www.sciencedirect.com/science/article/pii/S0012825219302636?via=ihub