Highly Iridescent Psiloceras Ammonite Fossil Shell Fragment Jurassic Watchet UK

Description

Highly Iridescent Psiloceras Ammonite Shell Fragment from Doniford Bay

This striking fossil specimen is a highly iridescent shell fragment from an ammonite belonging to the genus Psiloceras, recovered from the famous Blue Lias Formation at Doniford Bay near Watchet, Somerset, United Kingdom. The specimen displays beautiful natural iridescence across the preserved shell surface, a rare and visually striking preservation of the original ammonite shell material.

The fossil was discovered by our own team members, Alister and Alison, on 28 February 2026 along the fossil-rich shoreline of Doniford Bay. Following recovery, the specimen was carefully cleaned, prepared, and treated by Alison to stabilise the fossil while preserving the delicate iridescent shell layers.

The photographs in this listing show the exact specimen you will receive, carefully selected for its preservation and visual appeal. This fossil is a genuine ammonite specimen and includes a Certificate of Authenticity with a lifetime guarantee card confirming its authenticity.

Full sizing can be seen in the listing photographs.

Geological Origin – Blue Lias Formation, Somerset

This ammonite fragment originates from the Blue Lias Formation, a well-known sequence of alternating limestone and shale layers that form part of the Lower Jurassic geology of Somerset and the wider southwest of England.

These sediments were deposited approximately 201–190 million years ago during the earliest stages of the Jurassic Period. At that time, much of southern Britain was covered by a warm shallow epicontinental sea, where marine sediments accumulated on the seafloor.

The Blue Lias is particularly famous for its rich fossil record, preserving a wide range of Early Jurassic marine organisms including:

• Ammonites
• Belemnites
• Bivalves and gastropods
• Crinoids
• Marine reptiles such as ichthyosaurs and plesiosaurs

Doniford Bay is one of the most productive fossil locations within the Blue Lias exposures of Somerset, where coastal erosion continuously reveals new fossils along the shoreline.

Psiloceras – Early Jurassic Ammonite

The genus Psiloceras belongs to the family Psiloceratidae, one of the earliest groups of ammonites to appear following the end-Triassic extinction event. These ammonites are among the first representatives of Jurassic ammonite faunas.

Taxonomic classification:

• Phylum: Mollusca
• Class: Cephalopoda
• Subclass: Ammonoidea
• Order: Ammonitida
• Superfamily: Psiloceratoidea
• Family: Psiloceratidae
• Genus: Psiloceras

Psiloceras species are important biostratigraphic index fossils, widely used by geologists to identify and date the earliest Jurassic rock layers.

Morphology and Shell Structure

Ammonites were marine cephalopods closely related to modern squid, cuttlefish, and octopus. They possessed a spiral coiled shell divided internally into chambers, which were used to regulate buoyancy while swimming in the water column.

Typical features of Psiloceras ammonites include:

• A smooth, gently rounded shell surface
• A tightly coiled planispiral shell form
• Fine growth lines marking shell development
• Simple suture patterns characteristic of early ammonites
• Thin aragonitic shell layers that occasionally preserve iridescent colours

This specimen preserves part of the outer shell layer, which exhibits striking natural iridescence. The shimmering colours occur when microscopic layers of the original shell material remain intact and refract light.

This phenomenon is sometimes referred to as ammonite nacre preservation, similar to the iridescence seen in modern pearl shells.

Early Jurassic Marine Environment

During the Early Jurassic, the seas around Somerset supported a rich and diverse marine ecosystem. Ammonites such as Psiloceras were among the most abundant and successful marine animals of this time.

These cephalopods were active swimmers, using jet propulsion to move through the water while hunting small marine organisms including crustaceans and plankton.

The surrounding ecosystem included:

• Ammonites and belemnites
• Marine reptiles such as ichthyosaurs
• Bivalves and gastropods
• Echinoderms including crinoids

Fine sediment accumulating on the seabed occasionally buried shells and skeletal remains, allowing them to become preserved within the Blue Lias limestone layers.

Authentic Jurassic Fossil from Doniford Bay

This specimen represents a genuine ammonite fossil collected directly from the fossil-rich coastline of Somerset. Fossils discovered and prepared by experienced collectors from well-known British localities are particularly valued by collectors and enthusiasts.

Key features of this specimen include:

• Genuine Psiloceras ammonite shell fragment
• Highly iridescent preserved shell surface
• From the Blue Lias Formation
• Early Jurassic Period
• Collected at Doniford Bay, Watchet, Somerset, UK
• Discovered by Alister and Alison on 28 February 2026
• Cleaned, prepared, and treated by Alison
• Photographs show the exact fossil specimen you will receive
• Supplied with a Certificate of Authenticity and lifetime guarantee

This beautiful ammonite shell fragment makes an excellent addition to Jurassic fossil collections, ammonite displays, geology collections, and natural history exhibits, showcasing the remarkable preservation and beauty of marine life from the earliest Jurassic seas.