fossil

Fossilized sea urchin test (likely sand dollar fragment or echinoid fossil)

Echinoidea; calcitic echinoderm skeleton, chiefly CaCO₃

AI-generated identification · may be incorrect

Cream-colored, rounded, finely textured low-relief surface; composed of porous calcite plates. Mohs hardness about 3, white streak, dull to pearly luster, and commonly brittle with no prominent cleavage.

Identified August 22, 2026More fossil →

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Physical properties

Formation & geological history

A marine echinoid skeleton preserved by burial and mineral stabilization in carbonate-rich sediment, generally from the Cenozoic or younger marine deposits. The exact age cannot be determined from the image.

Uses & applications

Primarily a collectible, educational, or decorative fossil; not generally used industrially. Value is usually modest unless unusually complete, large, or from a documented locality.

Geological facts

The fine pattern likely represents fused ambulacral plates or tubercles from a sea urchin or sand dollar. Echinoid fossils are often mistaken for ordinary limestone pebbles because their calcitic skeletons weather to a chalky surface.

Field identification & locations

Look for repeating five-part radial symmetry, tiny pores, plate boundaries, and occasional tubercles; a drop of dilute acid may fizz, but can damage the specimen. Common in marine limestones and beach or quarry deposits worldwide.