Eozoön is a fossilized organism that dates back to the Precambrian era. Some synonyms for eozoön include stromatolite, microbialites, and microbial mats. These terms all refer to the layered structures created by microorganisms in ancient times. Stromatolites were formed by the trapping and binding of sediment by microorganisms living on the ocean floor. Similarly, microbialites refer to organic structures that were created by microbial activity, while microbial mats are thin layers of microorganisms living on the surface of sediment or rock. Although these terms are similar in meaning to eozoön, they refer specifically to the structures formed by microorganisms rather than the actual fossilized organism itself.