archaeozoic

a.	1.	(Zool.) Like or belonging to the earliest forms of animal life.
	2.	(Geol.) formed in or belonging to the earlier of two divisions of the Precambrian era.
n.	1.	the time from 1.5 billion to 5 billion years ago; the time when the earth's crust formed; a time when only unicellular organisms and the earliest forms of life are present.

Noun	1.	Archaeozoic - the time from 3,800 million years to 2,500 million years ago; earth's crust formed; unicellular organisms are earliest forms of life Synonyms: Archaeozoic aeon, Archean, Archean aeon, Archean eon, Archeozoic, Archeozoic eon
Adj.	1.	archaeozoic - formed in the earlier of two divisions of the Precambrian era; "archeozoic life forms" Synonyms: archeozoic