I was quite baffled by it. I could tell it was not a body fossil, but there was the thought that it could be a trace fossil, a remnant of animal activity. The near regularity of the ridges were what intrigued me, especially when I found another (sadly not pictured) which matched. I knew of no mineral process which could result in this and wondered if it might be some bizarre sedimentary structure which I had not come across.
It is two months since this was found and the study I have done in that time would have enabled me to say that it is neither a trace fossil nor a sedimentary structure. It is, however, possibly a result of animal activity. I had it looked at and was told that it is most likely the result of stone age man making flint axes, something my girlfriend found more exciting than fossils. In order to confirm it I would need to have it looked at by an archaeologist who knows a thing or two about flint carving. To round off, here is Lizzie posing with the find: