What is a fossil fuel that forms underground from partially decomposed plant material?

Coal is a fossil fuel that primarily originates from the remains of large plants that existed millions of years ago, during periods of extensive vegetation, such as the Carboniferous period. When plants die, they are buried under layers of sediment. Over time, the heat and pressure from these sediments lead to a process called carbonization, in which the organic material is transformed into coal.

This fossil fuel mainly consists of carbon along with various other elements, including hydrogen, sulfur, oxygen, and nitrogen. The formation of coal requires specific conditions, such as an absence of oxygen, which slows down the decomposition of plant material and allows it to accumulate over geologic timeframes.

While oil and natural gas also come from ancient organic materials, they primarily result from the decomposition of marine organisms and undergo different processes and conditions for their formation. Therefore, coal distinctly represents the fossil fuel that forms from partially decomposed plant material.