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 earliest evidence for life found so far is in a 3.8 billion-year-old rock, the Isua sediments, found in western Greenland. The evidence for life in these rocks does not come from fossilized remains, but from a peculiar chemical signature of living organisms.