fossil

Fossilized coral or stromatoporoid

Calcareous coral, likely an indeterminate fossil colonial coral (phylum Cnidaria)

AI-generated identification · may be incorrect

Cream to gray-brown, irregularly rounded specimen with abundant porous, concentric or corallite-like textures; composed mainly of recrystallized calcium carbonate (calcite). Mohs hardness about 3, dull to slightly earthy luster, no obvious cleavage, and moderate specific gravity (~2.6–2.8).

Identified September 14, 2026More fossil →

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Physical properties

Formation & geological history

A prehistoric marine colonial organism accumulated calcium-carbonate skeletons that were buried and lithified, commonly during the Paleozoic or Mesozoic eras. Groundwater later recrystallized and weathered the fossil.

Uses & applications

Primarily a teaching, display, and collector specimen; fossil limestone may also be used as aggregate or decorative stone, though this piece is not suited to construction.

Geological facts

The visible repeating pores and growth bands are biological structures rather than mineral crystals. An acid test may cause weak effervescence if calcite remains exposed.

Field identification & locations

Common in fossil-bearing limestones worldwide, including North America, Europe, and Australia. Identify by its repeated corallite or honeycomb pattern and test cautiously with dilute hydrochloric acid or vinegar.