Written by the Fiveable Content Team • Last updated September 2025
Verified for the 2026 exam
Verified for the 2026 exam•Written by the Fiveable Content Team • Last updated September 2025
Definition
Fossilized stromatolites are layered rock formations created by the growth of microorganisms, particularly cyanobacteria. They are some of the oldest known fossils on Earth, dating back over 3.5 billion years.
Related terms
Cyanobacteria: These are photosynthetic bacteria that played an important role in creating Earth's oxygen-rich atmosphere.
Microfossils: These are tiny fossils usually requiring a microscope to see and often include the remains or traces of single-celled organisms like cyanobacteria.
Sedimentary Rock: This is rock formed from sediment, including small particles of rocks and minerals and organic material. Stromatolites form within this type of rock.