fossil

Fossil coral or stromatoporoid fragment

Likely fossilized colonial coral; exact taxon indeterminate from image

AI-generated identification · may be incorrect

Dense, rounded, cream-to-brown silicified or calcitic material with radiating/porous skeletal texture; hardness roughly 3 (calcite) to 7 (silica), dull to slightly waxy luster, no obvious cleavage.

Identified August 29, 2026More fossil →

Explore Fossil coral or stromatoporoid fragment in the encyclopedia →

Identify your own rocks.

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

App Store Google Play

Physical properties

Dense, rounded, cream-to-brown silicified or calcitic material with radiating/porous skeletal texture; hardness roughly 3 (calcite) to 7 (silica), dull to slightly waxy luster, no obvious cleavage.

Formation & geological history

A marine colonial organism formed the original calcium-carbonate skeleton, later buried and fossilized by mineral replacement or cementation. Such fossils commonly date from Paleozoic–Mesozoic marine rocks, but age cannot be established visually.

Uses & applications

Primarily a collector’s specimen, educational fossil, or jewelry/ornamental material when polished; not generally used industrially.

Geological facts

The radial, cellular pattern resembles fossil coral, though weathered echinoid or other carbonate fossils are possible. A fresh broken or polished surface and magnification would improve identification.

Field identification & locations

Common in limestone and shallow-marine deposits worldwide, including North America, Europe, and Australia. Look for repeated corallite pores or septa; vinegar fizz suggests calcite, while no fizz may indicate silicification.