Science blog

Exploring science at the British Library

22 June 2023

Wild British Library: Snails, Sponges and Oysters – finding fossils at the British Library

Alongside the Animals exhibition the British Library hosts a permanent show of animal fossils, hiding in plain sight. As you cross the Piazza on a visit to the Library you tread on limestone brought from the Hauteville region of the French Jura. This stone formed in the early Cretaceous period (145 and 100 million years ago - Ma) in a warm, shallow sea, teeming with life. The commonest fossils found here are spiral gastropods, similar in appearance to auger snails found today. These snails are filter feeders, living partly buried in the mud and capturing particles of food as they pass by in the sea water. Other animals such as soft bodied marine worms have left no fossils, nevertheless, we can see the tracks of their burrows as dark streaks in the stone.

A photograph of brown limestone, showing fossils of molluscs and worm trails
Hauteville limestone


Outside the door of the Knowledge Centre a group of coin sized discs reveal the branches of a sponge, sliced in cross section. Compare this to a modern sponge such as the Mermaid’s Glove and again we see how little some marine animals have changed over the millennia.

A picture of stone with circular fossilised sponge cross-sections, about the size of a 1p coin for scale
Fossilised sponges, with a penny coin for scale


Entering the front door of the Library, the floor is made of Portland stone, formed in the Jurassic period (150-145 Ma) in another warm tropical sea. Fossil shells, similar to oysters, are scattered among calcareous algal pellets which show as small white patches.

Portland stone with fossilised shells visible, and a penny for scale
Portland stone flooring, with a penny to show scale


Moving to the Upper Ground Floor, Portland stone is laid alongside dark Purbeck marble, crowded with the fossil remains of bivalve mussels that thrived in a muddy fresh water lagoon.

Marble showing mussel fossils, smaller than a penny
Mussel fossils in marble, with a penny for scale


If you would like to find out more about our fossils and stones see our report A Geology of the British Library. Building stone makes an easily accessible introduction to geology; explore further with London Pavement Geology.

Written by and all photographs taken by Richard Wakeford (Science Reference Specialist, Retired)