As dead organic matter builds up underground, much of it compacts and forms into fossil fuels, which in turn can be used to produce oil as well as coal for the use of humans.
Like coal and natural gas, petroleum was formed from the remains of ancient marine organisms, such as plants, algae, and bacteria. Coal, natural gas, and petroleum are all fossil fuels that formed under similar conditions. Today, petroleum is found in vast underground reservoirs where ancient seas were located.
