Original sentence: As these early eukaryotes and prokaryotes were microscopic, most of the history of life describes simple microorganisms.It is only about a billion years ago in the Ediacaran period that complex multicellular organisms began to appear in the oceans
Edited sentence: The history of life was that of the unicellular eukaryotes, prokaryotes, and archaea until about a billion years ago when multicellular organisms began to appear in the oceans in the Ediacaran period