Fossils and art at Green Park underground station

Green Park Underground Station, in London, has recently undergone an extensive renovation. The new entrance and the pavement are now made of Portland Stone, a Jurassic limestone quarried on the Isle of Portland, Dorset. This stone has been widely used in London and elsewhere as a construction material since Roman times, and as a result it has become quite ubiquitous in this city. 
The sediment that originated this limestone contained abundant shells, particularly gastropods (snails) and bivalves. These shells where subsequently dissolved when the sediment hardened, but their casts have remained in the rock as hollows that reproduce the morphology of the original shells. These animals, and many other soft-bodied organisms that have not been preserved, flourished in a shallow, tropical sea, as Matt Loader explains in this video: This spot of urban fossils is now in Paleourbana's map, thanks to the pictures sent by David Whittaker and Jesús Rodrígued Mon. The English version of this description will be available soon. You can find additional information about these urban fossils in Dinosaurpalaeo blog.