Nanobacterium
Nanobacterium ( NAN-oh-bak-TEER-ee-əm, pl. nanobacteria NAN-oh-bak-TEER-ee-ə) is the unit or member name of a former proposed class of living organisms, specifically cell-walled microorganisms, now discredited, with a size much smaller than the generally accepted lower limit for life (about 200 nm for bacteria, like mycoplasma).