Mycoplasma genitalium, a parasitic bacterium which lives in the primate bladder, waste disposal organs, genital, and respiratory tracts, is thought to be the smallest known organism capable of independent growth and reproduction. some of these single-celled organisms are spheres about 0.3 micrometre in diameter, with a total mass of 10−14 gram—equal to that of 8,000,000,000 hydrogen atoms.
