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the existence of animal life; formed when there was no animal life on the globe; as, the azoic. rocks. Azoic age (Geol.), the age preceding the existence of animal life, or anterior to the paleozoic tome. Azoic is also used as a noun, age being understood. See Archæan, and Eozoic.

Of or pertaining to the Metazoa.

earliest period in geological period, extending up to the Lower Silurian. It includes an Azoic age, previous to the appearance of life, and an Eozoic age, including the earliest forms of life.