Fossil fuels refer to natural fuels derived from the remains of dead plants and animals. This includes coal, natural gas, and oil. These natural fuel sources are produced by the anaerobic decomposition of dead plants and animals from millions of years ago. Ancient earth is a lot different from what we know today. The climate was different, and the species that lived were different. The environment was different too. It was full of swamps, and various plants. As the plants die, they fall into swamps, and get buried under water. Since there is not much oxygen at the bottom of bodies of water, the decay is either really slow, or incomplete, and the remains decompose through a process called anaerobic decomposition. This process begins with bacterial hydrolysis that break down organic polymers into its derivatives. Other bacteria convert these into smaller compounds like amino acids, and sugars sugars, and further into carbon dioxide, acetic acid, and ammonia among others. Methanogens, th...