Fossilized Bivalve (Mussel or Clam)
Indeterminate species, cf. Mytilidae gen. et sp. indet. • Body fossil, invertebrate, specifically a bivalve mollusk
Geological Period
Likely Cretaceous to Neogene
Estimated Age
Approx. 5 to 100 million years
Preservation Type
Permineralization or replacement; the original shell material has likely been replaced by minerals like silica or phosphate, resulting in a dark, stony texture.
Condition Assessment
Fair; the specimen is worn (water-rolled), likely collected as beach float, with significant erosion of the hinge and fine morphological details.
Taxonomic Classification
Phylum: Mollusca, Class: Bivalvia, Order: Pteriomorphia (potential), Genus: cf. Mytilus or similar marine bivalve
Morphological Description
Small, fan-shaped to elongated shell fragment showing distinct radial ribbing and concentric growth lines. The specimen appears moderately convex with a dark, weathered surface and worn edges.
Rock Matrix
Mostly free of matrix, but showing traces of fine-grained silty or phosphatic sediment within crevices.
Formation & Location
Possible origin from coastal formations such as the Chesapeake Group (USA) or similar marine deposits in Europe or North Africa.
Size & Dimensions
Approximately 2-3 cm in length; typical for small adult or juvenile marine bivalves of this clade.
Value & Rarity
Estimated Market Value
$5 - $15 USD
Auction Estimate
$10 - $30 USD (usually sold as part of a lot)
Rarity Assessment
Common; bivalve fossils of this nature are abundant in marine fossil-bearing strata worldwide.
Scientific Significance
Provides evidence of local paleoenvironment (marine) and can contribute to understanding regional molluscan biodiversity and paleobiogeography.
Preparation Recommendations
No further mechanical preparation required. Store in a dry, stable environment. Can be cleaned gently with a soft brush and distilled water if necessary.
Notable Features
Heavy mineralization and dark coloration suggest it may have been found in a phosphatic bed or an area high in manganese/iron, resulting in its weathered, 'river-worn' appearance.