Rugose Coral (Horn Coral) Cross-Section
Rugosa incertae sedis (Solitary rugose coral cross-section) • Body fossil, invertebrate marine coral
Geological Period
Devonian (or potentially Ordovician to Permian)
Estimated Age
359 to 419 million years
Preservation Type
Permineralization and complete replacement by secondary minerals (likely silica or calcite recrystallization)
Condition Assessment
Good condition for an eroded natural cross-section; displays clear internal radial structures although the outer epitheca is partially weathered
Taxonomic Classification
Phylum Cnidaria, Class Anthozoa, Order Rugosa
Morphological Description
The specimen exhibits a circular to slightly oval cross-sectional view of a solitary coral. Radiating septa are clearly visible extending inward from the outer wall toward the center, along with visible internal tabulae or dissepiments, creating a wheel-like or starburst pattern characteristic of rugose coral corallites.
Rock Matrix
Silicified limestone or calcareous mudstone matrix
Formation & Location
Commonly found in Paleozoic marine sedimentary formations globally, such as the Onondaga Formation in North America or similar limestone-rich strata in Europe
Size & Dimensions
Approximately 3 to 4 cm in diameter, falling within the normal size range for solitary rugose corals
Value & Rarity
Estimated Market Value
10 to 30 USD
Auction Estimate
15 to 25 USD
Rarity Assessment
Common
Scientific Significance
Provides valuable insight into Paleozoic shallow marine reef ecosystems and the evolutionary history of early colonial and solitary anthozoans
Preparation Recommendations
Gentle washing with water and a soft brush to remove loose dirt. No heavy acid preparation needed as the natural weathering has already exposed the cross-section. Store in dry conditions.
Notable Features
The specimen features a naturally weathered transverse cross-section that cleanly exposes the internal septal arrangements without the need for manual cutting or polishing.