Rock Identifier
Fossil shell or shell fragment (Likely a calcareous bivalve or gastropod fragment; precise identification requires locality and microscopy) — fossil
fossil

Fossil shell or shell fragment

Likely a calcareous bivalve or gastropod fragment; precise identification requires locality and microscopy

AI-generated identification · may be incorrect

Pale cream to pink, matte, and irregularly triangular, with fine growth lines and layered fibrous texture. Likely calcite/aragonite; Mohs hardness about 3–4, with weak to moderate cleavage and specific gravity roughly 2.6–2.9; dilute acid may effervesce.

Identified More fossil →
Explore Fossil shell or shell fragment in the encyclopedia →

Identify your own rocks.

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

App StoreGoogle Play

Physical properties

Pale cream to pink, matte, and irregularly triangular, with fine growth lines and layered fibrous texture. Likely calcite/aragonite; Mohs hardness about 3–4, with weak to moderate cleavage and specific gravity roughly 2.6–2.9; dilute acid may effervesce.

Formation & geological history

A biological shell formed in marine or freshwater conditions, later buried and mineral-preserved or partially recrystallized. Geological age cannot be determined from the photograph alone.

Uses & applications

Primarily a natural-history or educational specimen; intact examples may be used in jewelry, décor, or collections, while fragments have little industrial value.

Geological facts

The visible curved growth bands are characteristic of shell growth rather than igneous or metamorphic texture. Pink coloration can result from original shell pigments, staining, or mineral alteration.

Field identification & locations

Look for concentric growth lines, a shell-like layered structure, and acid reaction; compare with local fossil guides. Common in limestone, coastal deposits, river gravels, and shell beds.

More like this

Other fossil specimens

Probable fossil-bearing rock or mineral concretion (Unidentified carbonate-rich concretion with a possible fossil inclusion) — fossil

Probable fossil-bearing rock or mineral concretion

Unidentified carbonate-rich concretion with a possible fossil inclusion

fossil
Likely fossil oyster shell (Fossilized bivalve shell; exact species cannot be identified from the image) — fossil

Likely fossil oyster shell

Fossilized bivalve shell; exact species cannot be identified from the image

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

Crinoid Stem Fossil in Matrix

Phylum Echinodermata, Class Crinoidea

fossil
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)

sedimentary
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)

fossil
Rounded sedimentary pebble (Likely micritic limestone or calcareous sandstone) — sedimentary

Rounded sedimentary pebble

Likely micritic limestone or calcareous sandstone

sedimentary