How have scientists come to understand what life looked like long ago and how does this explain where fossil fuels came from?

Scientists use a variety of methods, such as studying fossils, sedimentary rock layers, and geochemical analysis, to understand what life looked like long ago. Fossil fuels were formed from the remains of ancient organisms, like plants and microorganisms, that lived millions of years ago. Over time, the organic matter was buried and subjected to heat and pressure, transforming it into fossil fuels like oil, coal, and natural gas.