Coral-derived Fossil Pebble (likely Porifera or Anthozoa)
Inert pebble-worn fossil; cf. Chaetetes or fossilized Spongiomorphid • Body fossil; Marine invertebrate (Sponge or Coral)
Geological Period
Likely Paleozoic to Mesozoic (Devonian or Cretaceous are common for these lithologies)
Estimated Age
Approximately 100 to 400 million years
Preservation Type
Silicification or Calcification; heavily weathered and rounded by water transport (fluvial or marine erosion)
Condition Assessment
Fair; significantly eroded and water-worn, lacking fine structural details or diagnostic internal septa.
Taxonomic Classification
Phylum: Porifera (Sponges) or Cnidaria (Corals); Class: Anthozoa or Demospongiae
Morphological Description
Sub-rounded, water-worn pebble displaying a porous, pitted surface. Small ostia (pores) are visible across the surface, representing the original skeletal structure of a colonial organism. The texture is granular and weathered.
Rock Matrix
The specimen itself is the mineralized remains, likely composed of chert, flint, or dense limestone with secondary silica replacement.
Formation & Location
Commonly found in glacial till, riverbeds, or coastal shingles; likely sourced from formations like the Chalk Group (UK) or Devonian limestones (USA/Midwest).
Size & Dimensions
Approx. 3-5 cm in diameter; consistent with typical small fossiliferous pebbles found in secondary deposits.
Value & Rarity
Estimated Market Value
$1 - $5 USD
Auction Estimate
N/A (Generally sold in bulk lots or found by beachcombers)
Rarity Assessment
Common; these types of weathered marine fossils are ubiquitous in certain geological regions.
Scientific Significance
Low; represents a common paleo-environmental indicator of ancient shallow marine shelf ecosystems, but lacks the stratigraphic context for high-level research.
Preparation Recommendations
Keep dry; no chemical preparation required. Can be lightly polished to reveal internal skeletal patterns if desired.
Notable Features
High degree of rounding suggests a long history of transport from its original source rock; distinctive 'pock-marked' appearance from weathered skeletal canals.