fossil

Fossiliferous limestone with possible shell fossils

Bioclastic limestone, composed mainly of calcite (CaCO₃)

AI-generated identification · may be incorrect

Pale gray, weathered, fine- to medium-grained stone with visible curved fossil or shell impressions and rusty surface staining. Calcite has Mohs hardness 3, vitreous to dull luster, rhombohedral cleavage, and reacts vigorously with dilute hydrochloric acid; exact texture is obscured by weathering.

Identified August 14, 2026More fossil →

Explore Fossiliferous limestone with possible shell fossils 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 when marine shells and skeletal debris accumulated, were compacted, and cemented on an ancient seafloor; age cannot be determined from the photograph and may range from Paleozoic to Cenozoic. Weathering has exposed the fossil structures and produced iron-oxide staining.

Uses & applications

Collected as a fossil specimen, educational sample, or decorative stone; limestone is widely used for cement, aggregate, and building stone, but this piece is probably too small and irregular for construction use.

Geological facts

The curved features may represent bivalves, gastropods, or other marine organisms, though they could also be weathering cavities. Acid testing and a close examination of the impressions are needed for confident fossil identification.

Field identification & locations

Common in marine sedimentary formations worldwide, especially coastal and former seabed regions. Confirm limestone with a vinegar or dilute acid fizz; avoid damaging potentially important fossils, and use a hand lens to inspect shell walls or internal structure.