Description
An exquisite High Grade Sliced and Polished Fossil Slab containing numerous Promicroceras marstonense ammonites from the iconic Marston Marble of Marston Magna, Somerset, UK. These beautiful ammonites are preserved in dark, fine-grained limestone, part of the Obtusum Zone in the Lower Lias, dating to the Lower Jurassic (~195–200 million years ago).
Promicroceras marstonense is one of the most characteristic and sought-after ammonites from this region, known for its compact size, detailed ribbing, and aesthetic arrangement in dense fossiliferous layers. The slab has been expertly cut and polished to reveal the structure, colour contrast, and detail of the ammonites embedded within the matrix.
Fossil Type: Ammonite (extinct marine cephalopod)
Species: Promicroceras marstonense
Geological Age: Lower Jurassic – Obtusum Zone, Lower Lias
Formation: Marston Marble (Lower Lias Group)
Depositional Environment: This fossil slab was formed in a quiet, shallow marine setting where fine muds and silts accumulated and allowed for exceptional fossil preservation. Periodic anoxic conditions enhanced the conservation of hard-shelled marine organisms, particularly ammonites.
Morphological Features:
- Small, finely ribbed ammonites with evolute coiling
- Dense assemblage of ammonites in natural orientation
- Highly polished surface highlights growth lines and fossil detail
Notable:
- High-grade decorative and scientific fossil slab
- Classic fossil locality from British palaeontology
- Ideal for display, collectors, or educational purposes
- The exact specimen shown is the one for sale
Authenticity: All of our fossils are 100% genuine natural specimens and are provided with a Certificate of Authenticity. Please refer to the scale cube in the image (1cm per square) for full sizing details.
This Promicroceras marstonense ammonite slab is a true collector’s item—both a window into Early Jurassic marine life and a beautiful geological showpiece from the famed fossil beds of Somerset.





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