Cretaceous Fossil Sponge Dorset UK Branscombe Grey Chalk Marine Specimen

Overview & Authenticity

Offered here is a genuine Cretaceous fossil sponge collected from the Grey Chalk Subgroup at Branscombe, Dorset, UK. This is a carefully chosen British marine fossil specimen, selected for its preservation quality, distinctive natural form, and excellent display character. The photographs show the actual fossil you will receive, ensuring complete transparency and confidence when purchasing.
Every fossil is supplied with a Certificate of Authenticity, including a lifetime guarantee of genuineness, provided on a generic authenticity card.

This specimen was personally discovered by our own experienced team members Alister and Alison on 20 January 2024, and has been professionally cleaned, prepared, and treated by Alison, ensuring it is stabilised and ready for long-term collection or display.

Geological Setting – Grey Chalk Subgroup, Branscombe

Branscombe is a classic coastal fossil locality in southern England, known for its impressive chalk exposures and rich marine fossil record. During the Late Cretaceous, this region lay beneath a warm, shallow epicontinental sea that covered much of Britain.
The Grey Chalk Subgroup was deposited approximately 100–94 million years ago, during the early Late Cretaceous. Chalk formed through the gradual accumulation of microscopic carbonate plankton, creating soft seafloor sediments that were ideal for preserving marine organisms in fine detail.

Fossil Type & Biological Origin

Sponges belong to the phylum Porifera, one of the oldest animal groups on Earth. In Cretaceous seas, sponge communities were widespread and played a vital role as filter feeders, processing seawater for organic nutrients and contributing to the structure of marine carbonate ecosystems.
Fossil sponges are especially valued for their unusual morphology and the insight they provide into ancient seabed habitats. Many chalk sponges had supportive skeletal frameworks that allowed them to fossilise in strong three-dimensional form.

Morphology & Notable Features

This specimen preserves the characteristic external body structure of a marine sponge, often showing an irregular but coherent growth shape shaped by its natural filtering architecture. Surface textures may display subtle pore impressions, gentle ridging, or sculptured contours typical of chalk sponge fossils.
The pale grey-white chalk matrix provides attractive contrast, making the fossil’s outline and form stand out clearly. Alison’s careful preparation work has revealed the fossil while preserving its authenticity and natural integrity.

Depositional Environment & Fossilisation

During the Late Cretaceous, Branscombe lay beneath calm shallow seas with minimal sediment disturbance. Sponges lived attached to the seabed alongside echinoids, bivalves, ammonites, and other marine invertebrates.
After death, sponge remains were gently buried within fine carbonate mud. Over millions of years, mineral replacement and lithification transformed the organism into stone while preserving its external form. Chalk environments are particularly important for preserving delicate marine fossils due to their low-energy depositional conditions.

Collecting & Display Value

British chalk fossils from Dorset are highly sought after for their scientific significance, strong provenance, and visual appeal. A fossil sponge from Branscombe represents a tangible connection to the warm Cretaceous seas that covered Britain during the age of dinosaurs.
Full sizing details are provided in the photographs. As a team-collected, expertly prepared specimen supplied with a Certificate of Authenticity and lifetime guarantee, this fossil sponge is ideal for collectors, educational collections, or museum-style display.