Over a wide range of living species from rotifer to sequoia it was shown that there is positive correlation between species longevity and linear size (r = 0.93, n = 186), as well as between species longevity and mass (r = 0.94, n = 37). Real slope of correlation line longevity on mass may be near 0.27. So, for all studied species exist the general low- the more its mass (or weight, or volume), the longer its life span. It is possible that between mass (or volume) and longevity of living things there is causal relation.