What formed as a result of bacteria acting on plants that died millions of years ago?

As a result of bacteria acting on plants that died millions of years ago, fossil fuels such as coal, oil, and natural gas were formed. These organic materials underwent decomposition and transformation over millions of years under heat and pressure, creating energy-rich resources. This process also contributed to the formation of peat, which can eventually turn into coal, depending on environmental conditions. Fossil fuels are now crucial energy sources for modern civilization.