Answer: The answer is When Tiny Algae and Plankton decompose under conditions of heat, pressure and low oxygen
Explanation:
Micro or tiny algae contain lipid and fatty acids as membrane components. In areas where algae are grown in are low oxygen and carbon dioxide enriched air it can be converted to oily substances.
For the oil to form, the tiny algae and plankton sink into the bottom of the ocean and mix with inorganic clay-like materials. the mud cannot be exposed to too much oxygen thereby creating an anoxic environment. This is known as shale, if it is buried between 2-4km the temperature and pressure increases thereby transforming it into a waxy material called Kerogen, a shale that contains this material is called oil shale