Why are coal and oil and natural gas called fossil fuels?

Answer 1

Coal, petroleum,and natural gas, are called fossil fuels because they were formed millions of years ago, during the Carboniferous period.

Answer 2

These resources are called fossil fuels because they are formed over millions of years from the remains of ancient plants and animals. As these organisms decomposed under heat and pressure in the Earth's crust, they transformed into coal, oil, and natural gas. This process gives them the classification of "fossil" fuels due to their organic origins.