For a basic 500 square feet project in zip code 47474, the benchmark cost to Insulate Your Home ranges between $0.63 - $1.43 per square foot* . To estimate costs for your project: 1.
So in answer to your question, the oldest fossils are stromatolites, and the life forms that created those fossils were prokaryotic bacteria and algae like cyanobacteria.
The fossils are known as stromatolites and are the evidence of ancient water-based bacterial colonies, which cemented sediments together into distinctive layers with carbonate. Before this new discovery, the oldest known fossils were 3.48-billion-year-old stromatolites found in Western Australia.