Serpulid Cycloserpula intestinalis Fossil Kimmeridge Clay Jurassic Dorset UK A-Grade

Description

Serpulid Cycloserpula intestinalis Fossil – Kimmeridge Clay, Jurassic, Wyke Regis, Dorset, UK

This beautifully preserved Serpulid Cycloserpula intestinalis fossil comes from the world-famous Kimmeridge Clay Formation at Wyke Regis, Dorset, a site renowned for yielding exceptional Late Jurassic marine fossils. Each specimen, typically 45–80 mm, displays the characteristic coiled calcareous tube of this unique serpulid worm. The photographs show a representative example of the fossil you will receive, selected for clarity and quality. A 1 cm scale cube is included for size reference. All of our Fossils are 100% Genuine Specimens and come with a Certificate of Authenticity.

Geological Age and Formation

This fossil originates from the Kimmeridgian Stage of the Late Jurassic (approx. 157–152 million years ago). The Kimmeridge Clay Formation, stretching along the Dorset coastline, forms part of the celebrated Jurassic Coast UNESCO World Heritage Site. These deep marine mudstones were deposited in a quiet, oxygen-poor basin within the ancient Kimmeridge Sea, allowing exceptional preservation of delicate marine organisms.

The dark, organic-rich clay reflects an anoxic seabed where low oxygen levels slowed decay, creating ideal conditions for fossilisation. This environment preserved ammonites, marine reptiles, fish, bivalves, and invertebrate encrusters such as serpulid worms.

Fossil Type, Species, and Classification

Fossil Type

• Serpulid Worm Tube, formed by a sessile polychaete that secreted a calcareous spiral tube anchored to hard substrates.

Species and Taxonomy

• Species: Cycloserpula intestinalis
• Genus: Cycloserpula
• Family: Serpulidae
• Order: Sabellida (Polychaeta)
• Class: Errantia
• Phylum: Annelida

This species is one of the most recognisable serpulids of the Jurassic, well known for its tightly coiled, sometimes irregular tube structure.

Morphological Features

These fossils display the distinctive traits of Cycloserpula intestinalis, including:

• Spiral or helical tube structure, often tightly coiled
• Smooth to gently ridged exterior formed by incremental growth
• Calcareous tube composition, secreted by the worm for protection
• Consistent diameter along the spiral, reflecting steady growth
• Strong attachment base, showing where the worm anchored to shells or other seafloor materials
• Fine preservation enabling easy identification

Serpulids lived permanently attached to surfaces, filtering food particles from seawater using feathery radioles (soft feeding appendages), which do not fossilise—leaving only the durable tube behind.

Depositional Environment

The Kimmeridge Clay represents:

• Deep, stagnant marine waters
• High organic productivity
• Anoxic bottom conditions
• Fine mud deposition uninterrupted by wave action

These conditions allowed delicate organisms such as serpulid tubes to fossilise intact. Cycloserpula intestinalis commonly colonised ammonite shells, driftwood, and other skeletal debris on the seabed, forming mini-ecosystems known as benthic encrustation communities.

Biozone and Scientific Context

The Kimmeridge Clay contains several well-known ammonite biozones, such as:

• Aulacostephanus eudoxus Zone
• Aulacostephanus autissiodorensis Zone

Serpulid fossils within these units assist paleontologists in:

• Reconstructing paleoecology
• Identifying encrusting communities
• Understanding substrate availability in the Jurassic sea
• Mapping marine biodiversity within the Kimmeridgian sediments

Cycloserpula intestinalis is frequently used in ecological studies of Jurassic seafloor colonisation.

Collector Grade and Display Appeal

Each specimen has been carefully selected for:

• Well-defined spiral structure
• Strong preservation of tube morphology
• Attractive natural colouration from the mineral-rich clay
• Clean presentation suitable for study or display
• Stable matrix and durable fossil integrity

Their unique coiled forms make these fossil serpulid tubes fascinating additions to any collection.

Ideal for Collectors, Educators, and Jurassic Fossil Enthusiasts

This Serpulid Cycloserpula intestinalis from the Kimmeridge Clay offers a rare glimpse into the benthic life of the Jurassic seas. Its geological significance, excellent preservation, and elegant natural structure make it a perfect specimen for collectors, educational purposes, or anyone fascinated by Britain’s rich fossil heritage.