Dactylioceras
These Dactylioceras ammonites come from a rich succession of Jurassic beds on England's Yorkshire coastline. They are about 180 million years old and were spiral-shelled relatives of octopus and squid. Ammonites died out in the same extinction event that killed off the dinosaurs 65 million years ago. Most of these have a base cut, so they stand up nicely.
3-5cm on matrix
