Rock Identifier
Fossilized shell or coral fragment (Indeterminate biogenic carbonate; likely calcite/aragonite (CaCO₃)) — fossil
fossil

Fossilized shell or coral fragment

Indeterminate biogenic carbonate; likely calcite/aragonite (CaCO₃)

AI-generated identification · may be incorrect

Cream to tan, porous and weathered, with possible shell or coral texture and a darker mineral-filled cavity. Carbonate fossils are typically Mohs 3–4, vitreous to dull, and may preserve original layered or chambered structure.

Identified More fossil →
Explore Fossilized shell or coral fragment in the encyclopedia →

Identify your own rocks.

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

App StoreGoogle Play

Physical properties

Cream to tan, porous and weathered, with possible shell or coral texture and a darker mineral-filled cavity. Carbonate fossils are typically Mohs 3–4, vitreous to dull, and may preserve original layered or chambered structure.

Formation & geological history

Formed when a marine organism’s shell or skeleton was buried in sediment and mineralized during diagenesis; age cannot be determined from the image. Common in limestone and shallow-marine sedimentary deposits.

Uses & applications

Used mainly for education, collecting, decoration, and paleontological study; larger attractive specimens may enter the fossil market.

Geological facts

The specimen appears to be a genuine geological fossil rather than a manufactured object, but the visible features are insufficient for precise taxonomic identification.

Field identification & locations

Test with dilute vinegar or hydrochloric acid: calcite-rich material effervesces, though testing can damage it. Look for repeated biological symmetry, growth lines, pores, or chambers; common sources include limestone regions worldwide.

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
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

sedimentary
Weathered fossil bone fragment (identification uncertain) (Fossilized bone; exact taxon and mineral composition cannot be determined from the image) — fossil

Weathered fossil bone fragment (identification uncertain)

Fossilized bone; exact taxon and mineral composition cannot be determined from the image

fossil