I found the pilgrims standing at the wall above the abbey guest house. From a distance, the biscuit-coloured stonework looked ordinary enough; coming closer, I realised what they were looking at. One stone was a block containing a huge curled horn.“It’s an ammonite,” Peter was explaining. “A fossil of the ancient sea.” The intricate stone spiral held everyone’s attention. When dinosaurs walked the earth, ammonites, ancestors of modern-day squids, would have swum the oceans. The valley below the abbey would have been a bay in one of these shallow tropical seas. “That’s where our ammonite swam,” Peter informed us. “Although what we’re looking at is just the shape the creature made in mud, its imprint in the seabed.”On d