simple life form
- microbeMicroscopic living organism
- amoebaShape-shifting single-celled organism
- bacteriaNucleus-free single-celled organisms
- cellBasic unit of life
- organismLiving biological entity
primordial · single-celled · germ · plankton · algae · protozoa · primitive · microscopic · ooze · pond · slime · spore · nucleus · membrane · flagella · dividing · replicating · evolution
biological complexity
simple life formvertebrate
Spinal column animal
mammal · intelligent life · human being · sentient being · primate
organizational scale
simple life formmegafauna
Species over 44 kilograms
colonial organism · superorganism · whale · elephant · giant squid