Calyptraea sp. (Silicified Slipper Snail/Cup-and-saucer shell)
Calyptraea cf. centralis • Body fossil (Invertebrate Gastropod); Silicified mineral replacement
Geological Period
Neogene (likely Miocene or Pliocene)
Estimated Age
5 to 23 million years
Preservation Type
Siliceous replacement (petrifaction). The original calcium carbonate shell has been replaced by silica, resulting in a geodized appearance with internal crystal growth.
Condition Assessment
Good (Fossil is complete in form but has lost fine surface detail due to coarse crystallization).
Taxonomic Classification
Phylum: Mollusca, Class: Gastropoda, Family: Calyptraeidae, Genus: Calyptraea
Morphological Description
Specimen exhibits a low conical, cap-like shape with an internal shelf or septum (the 'cup' in cup-and-saucer). The surface consists of druzy chalcedony/quartz crystals that have obscured original shell ornamentation while retaining the overall patelliform (limpet-like) silhouette.
Rock Matrix
Small fragments of fossiliferous limestone or sandy calcarenite partially adhering to the underside; largely free of matrix.
Formation & Location
Commonly found in the Hawthorn Group or Tamiami Formation of Florida, USA, often within 'silicified shell beds'.
Size & Dimensions
Approximately 3-5 cm in diameter; consistent with adult specimens of larger Neogene Calyptraea species.
Value & Rarity
Estimated Market Value
$15.00 - $35.00 USD
Auction Estimate
$20.00 - $50.00 USD
Rarity Assessment
Common; frequently found in regional localized lag deposits where silica-rich groundwater has altered shell beds.
Scientific Significance
Illustrates the process of permineralization and silica replacement in Cenozoic marine environments; provides data on shallow-water epifaunal gastropod populations.
Preparation Recommendations
Keep dry; no further chemical preparation needed. Display on a dark stand to highlight the translucency of the crystals. Avoid acidic cleaners which could damage any remaining calcareous matrix.
Notable Features
The entire shell has been transformed into a mini-geode, with micro-crystalline quartz facets reflecting light across the dorsal surface of the shell.