Britannica Sources used in this answer

How did ancient algae contribute to crude oil and natural gas deposits?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

“mermaid's wine glass” algae — Algae The macroscopic genus of algae known as *Acetabularia* is commonly called “mermaid's wine glass” because of the distinctive umbrella-like shape of the tips of its stalks.

Ancient algae played a foundational role in the creation of crude oil and natural gas deposits by serving as a primary source of organic matter. Along with other planktonic organisms, algae accumulated in ancient lakes and seas, where their remains were buried under fine-grained sediments in environments lacking free oxygen.123

This rapid burial preserved the organic tissue, preventing complete decay. Over geologic time, these deposits underwent biological and chemical changes, transforming into a complex, waxy mixture of hydrocarbon compounds known as kerogen. As this material was buried deeper and subjected to increased heat and pressure, the kerogen broke down into liquid petroleum and gaseous hydrocarbons.13

Additionally, during the early stages of decomposition, anaerobic microorganisms acting on this organic matter generated biogenic methane gas. These hydrocarbons eventually migrated from source beds into more permeable reservoir rocks, where they were trapped by nonporous barriers to form the commercial deposits extracted today.145