Rock Identifier
Likely coral fragment or calcareous fossil (Aragonite/calcite (CaCO₃), possibly fossil coral such as Pocillopora or a bryozoan) — fossil
fossil

Likely coral fragment or calcareous fossil

Aragonite/calcite (CaCO₃), possibly fossil coral such as Pocillopora or a bryozoan

AI-generated identification · may be incorrect

Small cream-white, porous, rounded pieces with a dull to slightly pearly luster; likely Mohs 3–4, low-to-moderate specific gravity, and no obvious cleavage. The repeated honeycomb-like pores suggest skeletal carbonate rather than a crystalline mineral.

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Physical properties

Small cream-white, porous, rounded pieces with a dull to slightly pearly luster; likely Mohs 3–4, low-to-moderate specific gravity, and no obvious cleavage. The repeated honeycomb-like pores suggest skeletal carbonate rather than a crystalline mineral.

Formation & geological history

Marine organisms built calcium-carbonate skeletons; later burial and lithification or beach weathering produced these fragments. Fossil age is indeterminate from the image, potentially modern beach material or Quaternary fossil coral.

Uses & applications

Primarily a collector specimen or aquarium decoration; carbonate material may be used for lime, cement, and soil neutralization, though these pieces have little industrial value.

Geological facts

Vinegar should fizz on a fresh surface, confirming carbonate. Coral identification requires visible corallite structure; similar textures occur in bryozoans, echinoids, and porous limestone.

Field identification & locations

The reported coastal Washington location (47.0°N, 124.2°W) makes beach-worn shell, bryozoan, or porous limestone more plausible than tropical fossil coral. Check for branching corallites, regular honeycomb cells, or shell-like layering; avoid acid testing valuable specimens.

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

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Crinoid Stem Fossil in Matrix

Phylum Echinodermata, Class Crinoidea

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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

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