Your fossil could be a fish jawbone. Fossil jawbones with teeth are sometimes found in Carboniferous Coal Measure rocks which are about 300 million years old. During the Carboniferous period Stoke-on-Trent had a tropical climate and was covered by swampy forest. When animals and plants died they sank to the bottom of the swamp and were quickly covered by more sediment, creating the ideal conditions for fossilisation.
Fish jawbones can often be very accurately identified  If you want to try and identify your fish jaw 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.