Brian Wright, age 10, of West, St. Paul, Minnesota, for his question:

Is it true that oil is formed from fossils?

Fossils are the remains of plants and animals that lived and died ages ago. They may be bones or many other things. Gobs of amber are fossilized resins that oozed from ancient pine trees. Actually, fossils may be any natural chemicals that were changed by living things. For example, living plant cells concentrate carbons and other materials. Many ancient forests were buried in the ground where heat and pressure drove off most of the other materials. After long ages, only the concentrated carbon was left as a layer of coal.

This is why we say that coal is a fossil fuel. Scientists suspect that the materials in buried petroleum were assembled by tiny plants and animals that teemed in the ancient seas. The main ingredients are hydrocarbon chemicals that only living cells can create from the earth's raw materials. This is why we say that oil is a fossil material. Its chemical ingredients were built by living things