Chain Coral or Syringoporid Coral Clast
cf. Syringopora sp. or Halysites sp. (weathered) • Body fossil; Invertebrate (Tabulate Coral)
Geological Period
Silurian to Devonian
Estimated Age
360 to 440 million years
Preservation Type
Silicification and replacement; the skeletal structure has been replaced by silica (chert/chalcedony), allowing it to survive high-energy water transport.
Condition Assessment
Fair; the specimen is a highly weathered, incomplete fragment of a larger colony, exhibiting significant fluvial abrasion and polished edges.
Taxonomic Classification
Phylum: Cnidaria; Class: Anthozoa; Subclass: Tabulata; Order: Heliolitida or Syringoporida
Morphological Description
The specimen exhibits a pattern of small, circular to oval apertures representing individual corallites within a colonial structure. The cross-sections show thin walls and a characteristic 'chain' or 'organ-pipe' arrangement typical of tabulate corals, though significantly rounded by water action. Distinguishable vertical tubes and possible horizontal connectors (phaceloid or cateniform growth) are visible as pitting.
Rock Matrix
Chert or silicified limestone; the specimen is likely a redeposited river or beach pebble where the matrix and fossil have been honed into a smooth clast.
Formation & Location
Commonly found in glacial till of the Great Lakes region (USA/Canada) or sedimentary basins of the Silurian Niagaran Escarpment.
Size & Dimensions
Approximately 2.5-3.5 cm in diameter; small for a full colony but typical for a water-worn pebble clast.
Value & Rarity
Estimated Market Value
$5 - $15 USD
Auction Estimate
$10 - $20 USD (as part of a bulk study lot)
Rarity Assessment
Common; these types of silicified coral pebbles are frequently found in gravel deposits and along shorelines in formerly glaciated regions.
Scientific Significance
Provides evidence of ancient reef-building communities in shallow, warm Paleozoic seas. These corals were major contributors to carbonate platform construction before the Permian extinction.
Preparation Recommendations
No further physical preparation required. Mild cleaning with water and a soft brush; can be lightly oiled or polished to enhance the visibility of the corallite structures.
Notable Features
Fine pitting representing the internal vascular-like structure of the coral colony; classic 'beach pebble' taphonomy showing the durability of silicified Paleozoic fossils.