Mikroorganismus

(microbiology) single-celled or noncellular spherical or spiral or rod-shaped organisms lacking chlorophyll that reproduce by fission; important as pathogens and for biochemical properties; taxonomy is difficult; often considered to be plants

considered ancient life forms that evolved separately from bacteria and blue-green algae

a large group of bacteria having rigid cell walls; motile types have flagella

any of diverse minute acellular or unicellular organisms usually nonphotosynthetic

primitive chlorophyll-containing mainly aquatic eukaryotic organisms lacking true stems and roots and leaves