Ammonite External Mold / Impression
Ammonoidea gen. et sp. indet. (faint coiled imprint, potentially cf. Perisphinctes or Hildoceras depending on exact locality) • Body fossil impression / external mold (Invertebrate)
Geological Period
Jurassic to Early Cretaceous
Estimated Age
140 to 180 million years old
Preservation Type
External impression / low-relief mold in fine-grained sedimentary matrix
Condition Assessment
Fair to Poor (highly weathered, incomplete impression lacking fine surface detail or original aragonite/calcite shell material)
Taxonomic Classification
Phylum Mollusca, Class Cephalopoda, Subclass Ammonoidea
Morphological Description
Extremely weathered faint circular and planispiral coiled imprint showing subtle concentric whorl outlines and faint ribbing impression on a broken limestone surface.
Rock Matrix
Light beige-buff to cream fine-grained micritic limestone / marlstone matrix with minor iron oxidation tinting
Formation & Location
Commonly found in Mesozoic marine limestone exposures across Western Europe (e.g., France, UK Jurassic Coast, Germany)
Size & Dimensions
Approximately 7–9 cm across for the rock hand specimen; coiled impression spans roughly 3–4 cm in diameter.
Value & Rarity
Estimated Market Value
$5 - $15 USD (nominal commercial value as a field specimen/educational sample)
Auction Estimate
$5 - $10 USD (typically sold in bulk study lots rather than individual auction lots)
Rarity Assessment
Common (ammonite impressions and fragments are ubiquitous in Mesozoic limestone deposits worldwide)
Scientific Significance
Provides local paleoenvironmental confirmation of a Mesozoic marine depositional setting, but offers minimal detailed taxonomic or evolutionary data due to heavy weathering.
Preparation Recommendations
No further mechanical preparation is recommended as the surface detail is very shallow and soft; store in a dry location and avoid acidic cleaning agents.
Notable Features
Exhibits a subtle, weathered central coil planispiral impression demonstrating how shell dissolved leaving an imprint on the soft mud seafloor before lithification.