Answer:
Stromatolites
Step-by-step explanation:
Stromatolites or stromatoliths are layered sedimentary formations that are created by photosynthetic cyanobacteria. These microorganisms produce adhesive compounds that cement sand and other rocky materials to form mineral “microbial mats”. In turn, these mats build up layer by layer, growing gradually over time. A stromatolite may grow to a meter or more. Although they are rare today, fossilized stromatolites provide records of ancient life on Earth. Hope this helps :)