This image shows another small art installation at Wren’s Nest, in “Snake Pit quarry”. Like so many of these names, we will never know why or how it got this name! The fossil sculpture depicts Poleumita, a gastropod (sea snail) which is sometimes found in these rocks. Dudley Museum has several examples, for example here, and here.
The rock behind is the Nodular Member of the Much Wenlock Limestone Formation, which was too impure to be used for smelting iron, hence it has been left behind. The quarry itself has been dug out of the Upper Quarried Limestone Member. This limestone was very pure (high in calcium carbonate content, and free of significant amounts of clay in it’s make-up) and was of great worth to the iron smelting industry. Indeed, so prized was it that the miners dug deep caverns as the followed the dipping beds down into the earth. Murchison commented in his Silurian System that:
“if the impure limestone … had been worth removing, the Wren’s Nest itself would long ago have been demolished, leaving only a central mound of shale to mark its former existence”