Rock Identifier

fossil

Stromatolite Fossil

Biogenic sedimentary structure (Stromatolite)

AI-generated identification · may be incorrect

Hardness varies around 3 to 4 on the Mohs scale depending on silicification; colors include tan, brown, and grey; dull luster; layered, concentric internal laminae structure.

Identified November 8, 2026More fossil →

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Physical properties

Hardness varies around 3 to 4 on the Mohs scale depending on silicification; colors include tan, brown, and grey; dull luster; layered, concentric internal laminae structure.

Formation & geological history

Formed through the trapping, binding, and cementation of sedimentary grains by micro-organisms, primarily cyanobacteria, in shallow water environments dating back billions of years.

Uses & applications

Valued as educational specimens, paleobiological research objects, and collector display pieces.

Geological facts

Stromatolites are among the oldest known fossils on Earth, providing ancient evidence of early photosynthetic life.

Field identification & locations

Identified in the field by distinct layered, dome-like or cabbage-like concentric structures in sedimentary limestone or chert formations.

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Crinoid Stem Fossil in Matrix (Phylum Echinodermata, Class Crinoidea) — fossil

Crinoid Stem Fossil in Matrix

Phylum Echinodermata, Class Crinoidea

Fossiliferous limestone (likely a crinoidal or shell-fragment limestone) (Bioclastic limestone, composed chiefly of calcite (CaCO₃)) — sedimentary

Fossiliferous limestone (likely a crinoidal or shell-fragment limestone)

Bioclastic limestone, composed chiefly of calcite (CaCO₃)

Porous limestone pebble (Calcite-rich limestone (primarily CaCO₃); exact identification is uncertain from the image) — sedimentary

Porous limestone pebble

Calcite-rich limestone (primarily CaCO₃); exact identification is uncertain from the image

Fossil oyster shell (Oyster (family Ostreidae); shell composed chiefly of calcite (CaCO₃)) — fossil

Fossil oyster shell

Oyster (family Ostreidae); shell composed chiefly of calcite (CaCO₃)