etched out of carboniferous limestone in the splash zone, halfway between Porteynon amd Rhossilli on the Gower Peninsula, South Wales, in a thin shelly band containing many spiral gastropods - are they gastropods, cephalopods ?
Did you bring any home with you? Did they look a bit like these?
These are tusk shells or Scaphopoda which are a sister group to cephalopods. I don't know much about them, and I am fairly new to fossil collecting myself but thought these were worth mentioning. Have a google and a read about them and see if they seem to match up to what you found.
thankyou very much for your interest, What put me off tusk shells was the fact the fossils weredead straight and I did not know how long ago tusk shells appeared in the fossil record. I Googled them as you suggested and in fact they have been documented from the Mississsippian, same as our Lower Carboniferous, and interestingly the earlier forms had smooth unmarked surfaces and lacked the curvature of later species, so we could be on to a winner here ! I've now found another band which is at Three Cliffs Bay which locates them in the High Tor Limestone beds. Serpulid worms were mentioned, as well as cephalopods, as possible alternatives, but I doubt they are worms. Now I am going to see if they have been described previously and see what they might say about the conditions these beds were laid down in: were they in the right environment for what we know about modern tusk shell biology ?
Thanks again and happy hunting !