Posted this on one of the stone forums and what I thought was flint in the first place appears to have some sort of fossil running in to the side of if it and protrudes either side Check it out and let me know what you experts think
Flint is a sedimentary rock so fossils are possible. Not sure what that ring is, but I can tell you what it's not. It's not a crinoid fossil as they were from the Mississippian time period and long gone by the Cretaceous period when your flint was formed. Gary
Flint like that is nodular. A concretion. Some of the nodular flints over here show concentric banding like a bull's eye. I'd guess it's something to do with that. Gary