Description
Overview & Authenticity
Presented 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 presence. The photographs show the actual fossil you will receive, ensuring full transparency and confidence for collectors.
Every specimen is supplied with a Certificate of Authenticity, including a lifetime guarantee of genuineness, provided on a generic authenticity card.
This fossil 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 the specimen is stabilised and ready for long-term preservation.
Geological Setting – Grey Chalk Subgroup, Branscombe
Branscombe is one of southern England’s most important chalk fossil localities, known for its striking coastal exposures and abundant marine fossils. During the Late Cretaceous, this entire 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 slow accumulation of microscopic carbonate plankton, creating fine soft seafloor sediments that preserved marine life in exceptional detail.
Fossil Type & Biological Origin
Sponges belong to the phylum Porifera, one of the oldest animal groups on Earth and among the earliest complex marine organisms. In Cretaceous seas, sponge communities flourished in clear, nutrient-balanced waters where they acted as essential filter feeders.
These organisms contributed significantly to carbonate shelf ecosystems, living alongside echinoids, ammonites, bivalves, and other marine invertebrates. Fossil sponges are especially valued because their preserved forms often reflect the growth structure of the living organism.
Morphology & Notable Features
This specimen preserves the characteristic external form of a marine sponge, often displaying an irregular but coherent growth shape shaped by its filtering architecture. The surface may show subtle pore impressions, gentle ridging, or sculptured contours typical of chalk sponge fossils.
The pale grey-white chalk matrix provides attractive contrast, allowing the fossil’s outline and natural structure to stand out clearly. Alison’s careful preparation work has revealed the fossil while maintaining its authenticity, stability, and geological integrity.
Depositional Environment & Fossilisation
During the Late Cretaceous, the Branscombe area lay beneath calm shallow seas with minimal sediment disturbance. Sponges lived attached to the seabed, filtering seawater and forming an important part of marine benthic communities.
After death, the sponge remains were gently buried within fine carbonate mud. Over millions of years, compaction, mineral replacement, and lithification transformed the organism into stone while preserving its three-dimensional external structure. Chalk deposits are particularly important for preserving such 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 importance, strong provenance, and striking aesthetic 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 serious collectors, educational collections, or museum-style display.
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