Rugose Coral (Horn Coral)
Rugosa gen. et sp. indet. (Solitary rugose coral, cf. Zaphrentis) • Body fossil, solitary invertebrate coral
Geological Period
Devonian (or potentially Carboniferous/Ordovician-Permian range)
Estimated Age
359 to 419 million years
Preservation Type
Permineralization and calcitic replacement with some secondary iron oxide (limonite/hematite) staining giving the reddish-brown discoloration on the exterior.
Condition Assessment
Fair to Good. The specimen is an incomplete fragment lacking the upper calyx (cup) opening, showing visible natural fracture planes and repaired cracks, but retaining clear external ornamentation.
Taxonomic Classification
Phylum Cnidaria, Class Anthozoa, Subclass Rugosa
Morphological Description
Cone-shaped solitary corallite showing distinct longitudinal septal grooves and ridges along the exterior wall (the epitheca). The specimen exhibits transverse growth wrinkles or rugosities indicating episodic growth, and a tapered proximal end where it originally attached to the substrate.
Rock Matrix
Free of major encrusting rock matrix, but retains traces of weathered argillaceous limestone or calcareous shale adhering to the lower section.
Formation & Location
Commonly found in Paleozoic marine sedimentary formations worldwide, such as the Onondaga Formation in North America or equivalent Devonian limestone strata in Europe.
Size & Dimensions
Approximately 3 cm in height, which is consistent with a small or juvenile solitary rugose coral specimen.
Value & Rarity
Estimated Market Value
10 to 30 USD
Auction Estimate
15 to 40 USD
Rarity Assessment
Common, widely distributed across global Paleozoic marine deposits.
Scientific Significance
Important for paleoecological reconstructions of ancient shallow marine tropical environments, reef ecosystems, and understanding the evolutionary history of Paleozoic cnidarians before the Permian-Triassic extinction event.
Preparation Recommendations
Gentle mechanical cleaning with a soft brush and water to remove residual sediment. Stabilize minor fractures with a diluted polyvinyl acetate (PVA) or appropriate consolidant if necessary. Store in a dry environment with stable humidity.
Notable Features
Distinct longitudinal septal markings and prominent reddish-brown iron oxide staining contrasting with lighter calcite areas, showcasing typical Paleozoic diagenetic alteration.