fossil

Fossilized coral or stromatoporoid fragment

Tabulate coral (e.g., Favosites) or stromatoporoid; exact identification requires microscopy

AI-generated identification · may be incorrect

Dark gray-brown, dense and partly lustrous, with a weathered honeycomb/radiating skeletal texture along the broken edge. The fossil carbonate framework is typically calcite; calcite hardness is Mohs 3 and it reacts with dilute hydrochloric acid.

Identified September 12, 2026More fossil →

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Physical properties

Formation & geological history

A colonial marine organism secreted a calcium-carbonate skeleton that was buried and lithified, commonly during the Paleozoic Era (about 541–252 million years ago). Tectonic exposure and weathering produced the present fragment.

Uses & applications

Primarily a fossil-collecting and educational specimen; polished pieces may be used decoratively, but it has little industrial value.

Geological facts

The repeated tubular or honeycomb pattern is characteristic of colonial reef-building organisms, not a crystalline igneous texture. The broad triangular shape appears to be a naturally weathered or cut fragment.

Field identification & locations

Look for regular corallites, pores, or radial partitions and test cautiously for fizz with dilute acid on an inconspicuous spot; avoid confusing it with slag or ordinary limestone. Paleozoic reef fossils occur widely in North America, Europe, North Africa, and Australia.