Rock Identifier
Fossilized Sand Dollar (Echinoidea (Clypeasteroida)) — fossil
fossil

Fossilized Sand Dollar

Echinoidea (Clypeasteroida)

AI-generated identification · may be incorrect

Hardness varies around 3 on the Mohs scale due to calcium carbonate composition; color ranges from white to greyish-tan; dull to earthy luster; calcareous test structure composed of fused plates

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Physical properties

Hardness varies around 3 on the Mohs scale due to calcium carbonate composition; color ranges from white to greyish-tan; dull to earthy luster; calcareous test structure composed of fused plates

Formation & geological history

Formed when ancient echinoids were rapidly buried in marine sediment, and their calcium carbonate skeletons were preserved or replaced by minerals over geological time, dating from the Cenozoic era or earlier

Uses & applications

Used primarily as educational specimens, decorative items, and prized pieces for fossil and shell collectors

Geological facts

The distinctive flower-like petal pattern on top represents the respiratory system (ambulacral grooves) of the once-living sea urchin relative

Field identification & locations

Found worldwide in marine sedimentary rock formations, especially in coastal areas and ancient sea beds; easily identified by their flattened, disc-like shape and dorsal star pattern

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

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Phylum Echinodermata, Class Crinoidea

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

Bioclastic limestone, composed chiefly of calcite (CaCO₃)

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Rounded sedimentary pebble

Likely micritic limestone or calcareous sandstone

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