Tabulate Coral (vuggy/eroded specimen)
Favosites sp. (likely cf. Favosites or Alveolites based on corallite structure) • Body fossil; Invertebrate (Cnidaria)
Geological Period
Silurian to Devonian
Estimated Age
360 - 430 million years
Preservation Type
Recrystallization and silicification; specimen shows significant vuggy porosity due to differential weathering.
Condition Assessment
Fair; the specimen is an eroded cobble with significant water-wear and lost fine detail, though the colonial structure remains identifiable.
Taxonomic Classification
Phylum: Cnidaria, Class: Anthozoa, Order: Tabulata, Family: Favositidae
Morphological Description
The specimen displays a honeycomb-like structure consisting of small, polygonal tubes (corallites). Transverse partitions known as tabulae are likely present within the tubes. The surface is heavily weathered, showing circular to hexagonal prismatic apertures.
Rock Matrix
Siliceous or calcitic replacement; likely originally from a limestone or dolostone matrix, though the matrix has been mostly removed.
Formation & Location
Commonly found in the Onondaga Formation (USA/Canada) or similar reef-building formations in the Midwest and Great Lakes region.
Size & Dimensions
Approximately 5-8 cm in length; typical for fragmentary colonial coral specimens found in glacial till or riverbeds.
Value & Rarity
Estimated Market Value
$5 - $15 USD
Auction Estimate
$10 - $30 USD (as part of a bulk natural history lot)
Rarity Assessment
Common; Favositid corals are among the most frequently collected Paleozoic invertebrates in North America and Europe.
Scientific Significance
Provides evidence of ancient warm, shallow marine environments (Paleozoic reef systems). Used in biozonation and paleogeographic reconstructions.
Preparation Recommendations
No intensive preparation needed; gentle washing with water and a soft brush to remove loose debris. Store in a dry environment.
Notable Features
Distinctive vuggy texture caused by the erosion of individual corallites, giving it a 'lava rock' or sponge-like appearance despite its biological origin.