What type of organisms contribute to the formation of natural gas?

The formation of natural gas primarily involves the decomposition of organic matter from simple aquatic plants and tiny marine animals. Over millions of years, the remains of these organisms, often found in sediment at the bottom of oceans or other water bodies, undergo processes of decomposition under heat and pressure. This transformation creates hydrocarbons, which are the main components of natural gas.

In aquatic environments, these tiny organisms, including phytoplankton and zooplankton, are prolific and form the base of the marine food web. When they die, their accumulation leads to the formation of organic-rich sediment layers. Over geological timescales, this organic material is subjected to anaerobic conditions, resulting in the formation of natural gas.

The other organisms listed do not play a direct role in the creation of natural gas. Large terrestrial mammals, terrestrial fungi, and bacteria, as well as large oceanic fish, are not typically involved in the specific processes that convert marine organic material into hydrocarbons under the unique conditions required for natural gas formation.