Fossilized Sponge / Invertebrate Impression Fragment
cf. Spongites / Ceraospongia / Porosphaera sp. (unidentified fossil sponge/invertebrate section) • Body fossil (poriferan/sponge fragment or mold impression), Marine Invertebrate
Geological Period
Jurassic (likely Upper Jurassic / Kimmeridgian - Tithonian, given regional context of Chablis/Yonne, France displayed on the background flyer)
Estimated Age
150 - 160 million years
Preservation Type
Permineralization / Recrystallization with calcite vein replacement and detailed external mold impression
Condition Assessment
Fair to Good; fragmentary specimen embedded in a irregular matrix block showing partial fibrous internal structure.
Taxonomic Classification
Phylum Porifera, Class Demospongiae or Hexactinellida (or potentially a large brachiopod/bivalve shell mold fragment)
Morphological Description
Exhibits a fan-shaped or concave surface structure with dense, fine fibrous or reticulated porous lines fanning outward from a central base. Outer margins feature crystalline calcite replacement crusts.
Rock Matrix
Dense fine-grained Jurassic limestone (micrite/chalky limestone) typical of the Paris Basin / Yonne region, with crystalline calcite deposits
Formation & Location
Likely from the Kimmeridgian or Oxfordian limestone strata of Northern/Central France (Yonne / Chablis region, Burgundy)
Size & Dimensions
Approximately 7-9 cm wide and 6-7 cm high (hand-held specimen matrix block)
Value & Rarity
Estimated Market Value
$15 - $40 USD
Auction Estimate
$20 - $50 USD
Rarity Assessment
Common to moderately common in regional French Jurassic marine limestone deposits.
Scientific Significance
Provides regional geological context for Jurassic shallow marine environments and benthic reef communities in the Anglo-Paris Basin.
Preparation Recommendations
Keep in a dry environment to prevent flaking; mild cleaning with a dry soft brush. Mechanical scribing could further reveal underlying structure.
Notable Features
Distinctive fan-like fibrous radial pattern surrounded by coarse white calcite crystalline veins along the matrix break boundaries.