fossil

Stromatolite Fossil

Stromatolite (Cyanobacteria biogenic sedimentary structure)

Mohs hardness around 3 to 7 depending on silicification; dull to earthy luster; distinct fine, wavy, concentric, or undulating laminations/layers; grayish-tan, beige, brown, and yellowish-tan color tones.

Identified July 26, 2026More fossil →

Explore Stromatolite Fossil in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed by the trapping, binding, and cementation of sedimentary grains by microorganisms, specifically cyanobacteria (blue-green algae), in shallow aquatic environments. These are among the oldest records of life on Earth, ranging from Precambrian (up to 3.5 billion years old) to modern day.

Uses & applications

Extremely valuable as educational and scientific display specimens, lapidary cabochons, polished decorative bookends or display stones, and collector fossils.

Geological facts

Stromatolites are among the oldest known fossils on Earth, dating back over 3.5 billion years. Photosynthetic cyanobacteria that created stromatolites were responsible for producing the oxygen that transformed Earth's early atmosphere (the Great Oxidation Event).

Field identification & locations

Identified in the field by characteristic fine, wavy, microbial laminations that create dome-like or column-like layered structures. Found in marine sedimentary formations worldwide, including Western Australia (Shark Bay), the United States (Wyoming, Michigan, Montana), and South Africa.

Other fossil specimens

See all

Crinoid Stem Fossil in Matrix

Phylum Echinodermata, Class Crinoidea

fossil

Sedimentary Outcrop (Sandstone/Shale)

Sedimentary bedrock formation (variable composition)

sedimentary

Chert with Fossil Brachiopod

Microcrystalline Quartz (SiO2) with Calcitic Brachiopod inclusion

sedimentary

Fossiliferous Limestone

Fossiliferous Calcilutite / Biomicrite

sedimentary

Fossilized Crinoid Stem in Limestone

Crinoidea (Class) in Calcium Carbonate (CaCO3) matrix

fossil

Fossiliferous Limestone

Limestone with embedded fossil cross-section

sedimentary