Wafer thin
Most ammonites in shale (compressed clay) are completely crushed flat and are preserved as an impression, sometimes with the white outline of the shell itself. That is why it’s not worth hammering into soft clay cliffs such as at Kimmeridge Bay; not only is it dangerous because of the risk of rock falls, it is just not worthwhile! The best fossils are washed onto the beaches where they can simply be picked up.
