fossil

Fossilized echinoid (sea urchin), likely a flint/chalk-associated test

Echinoid fossil; likely a regular echinoid such as Echinocidaris or related taxon, composed mainly of recrystallized calcite (CaCO₃)

AI-generated identification · may be incorrect

Off-white, rounded, and weathered with faint surface texture; original calcite plates and pore pairs may be obscured. Calcite has Mohs hardness 3, vitreous-to-dull luster, rhombohedral cleavage, and specific gravity about 2.7; dilute acid may effervesce unless silicified.

Identified August 12, 2026More fossil →

Explore Fossilized echinoid (sea urchin), likely a flint/chalk-associated test in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

At a glance

Common name: Fossilized echinoid (sea urchin), likely a flint/chalk-associated test
Scientific name: Echinoid fossil; likely a regular echinoid such as Echinocidaris or related taxon, composed mainly of recrystallized calcite (CaCO₃)
Category: fossil
Identified: August 12, 2026
Method: Standard

AI Estimated Value

About $5–$30 for a common weathered specimen; $50–$200 or more for large, sharply preserved examples with locality and taxonomic identification.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

The animal lived in shallow marine environments, and its test was buried in carbonate sediment before mineral preservation and compaction. Similar echinoids commonly date from the Mesozoic to Cenozoic, but the exact age requires locality and visible anatomy.

Uses & applications

Primarily a collectible and educational fossil; not generally used for construction or jewelry.

Geological facts

Echinoid tests are made of many interlocking calcite plates and often preserve fivefold radial symmetry, tubercles, and tiny ambulacral pores.

Field identification & locations

Look for five-part symmetry, plate sutures, rows of pores, or bumps where spines attached; a uniformly smooth surface may indicate heavy weathering or a naturally rounded limestone pebble. Common in marine limestone, chalk, and coastal deposits worldwide.