layered mounds of calcium carbonate that were deposited by algae during the Precambrian time
Explanation:
Are layers of mounts of columns shaped and are sheets of sedimentary rocks. Formed by the growth of the cyanobacteria. Various fossilized life on earth provides evidence of there formation and existence. The freshwater stromatolites in the British Colombia in Canada consists of the largest freshwater stromatolites and have been a field of research for NASA.
