Rugose Coral (Horn Coral)
Rugose coral cf. order Rugosa • Body fossil, invertebrate
Geological Period
Devonian to Carboniferous
Estimated Age
300 to 400 million years ago
Preservation Type
Permineralization and calcification / recrystallization within a worn pebble matrix
Condition Assessment
Good (worn and weathered on the outer matrix due to transport, but structural features of the coral skeleton remain clearly visible internally)
Taxonomic Classification
Phylum: Cnidaria, Class: Anthozoa, Subclass: Rugosa
Morphological Description
Elongated, somewhat conical or cylindrical corallite structure embedded in a water-worn pebble, displaying prominent parallel longitudinal septa and growth lines along the exterior surface.
Rock Matrix
Silicified limestone or quartz-cemented sandstone pebble (water-worn river or beach cobble)
Formation & Location
Glacial drift or alluvial gravel deposits, commonly derived from Paleozoic limestone formations worldwide (e.g., Midwestern United States, Western Europe)
Size & Dimensions
Approximately 10 to 12 cm in length, consistent with medium-sized solitary rugose corals
Value & Rarity
Estimated Market Value
$15 - $40
Auction Estimate
$10 - $30
Rarity Assessment
Common
Scientific Significance
Provides insights into ancient shallow marine tropical environments, reef ecosystems, and evolutionary history of early colonial and solitary corals.
Preparation Recommendations
Gentle washing with water and a soft brush to remove surface dirt; no mechanical preparation needed as nature has naturally polished the matrix.
Notable Features
The coral is naturally encased inside a smooth, water-worn cobble, creating a cross-sectional and longitudinal view of the skeletal walls and septa as the rock eroded.