sedimentary

Fossilized Echinoid (Sea Urchin)

Echinoidea (Class), often found as calcitic fossils

AI-generated identification · may be incorrect

Hardness: 3 (calcite composition); Color: Cream to white/light grey; Luster: Dull to earthy; Five-fold radial symmetry (pentamerism); Cleavage: Rhombohedral (on individual plate crystals); Specific Gravity: ~2.7.

Hardness: 3 (calcite composition)
Color: Cream to white/light grey
Luster: Dull to earthy

Identified April 6, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the permineralization or recrystallization of marine organisms' calcium carbonate shells within sedimentary layers, typically dating from the Ordovician period to the present.

Uses & applications

Primarily used for geological research, educational purposes, and as a popular collector's item; historically used in some cultures as amulets or 'thunderstones'.

Geological facts

In English folklore, these fossils were often called 'fairy loaves' because they resembled small loaves of bread. They are excellent index fossils used to date the rock layers in which they are found.

Field identification & locations

Identify by looking for a dome or heart shape with five visible lines radiating from the center (ambulacra). Commonly found in chalk pits, limestone quarries, or coastal cliffs.