A Paramecium.
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The simplest living organism is actually what is called Mycoplasma genitalium. It has a genome of only 580,000 base pairs and 482 protein-coding genes. Mycoplasma genitalium is a tiny parasitic bacteria that lives inside the digestive & genital tracts of certain monkeys & primates
Volvox
No. Bacteria are.
cell
spines
Bacteria
Sponges
A community is the simplest grouping of more than one organism in the biosphere.
Amoeba sponges
a community
amoeba
Organism.
The simplest level of multicellular organization occurs in colonial organism. A colonial organism also called a colony is an organism of a few to many cells that are loosely attached to each other and that show little or no specialization among themselves.