Your fossil could be a trilobite. Trilobites lived in the sea during the Cambrian, Ordovician and Silurian periods (550 to 400 million years ago) and can be found as fossils in a number of places in the British Isles including Wren's Nest in Dudley. The rocks near the surface in the Potteries area are not old enough to contain trilobite fossils - our rocks were formed about 100 million years after the trilobites died out!
Because trilobite shells often broke up soon after death, it is not uncommon to find bits of trilobite fossil rather than a whole specimen. Trilobites fossils are found sometimes rolled up in the defensive posture they would have adopted just before death.    
If you want to try and identify your trilobite fossil more precisely, you could search the Virtual Store or could take it to your local museum to be identified.
Click here to search the Virtual Store.