Top : A good sized Microderoceras ammonite (around 90mm).  The outer coil is just visible on the edge of the block.  These ammonites often have a crushed body chamber.  The middle will probably filled with caramel coloured calcite.  Microderoceras specimens also often have veins of calcite cutting through them, this one seems to hae avoided that.

Bottom Left:  Two Promicroceras ammonites

Bottom right:  Two nicely preserved Arnioceras ammonites, aesthetically arraned resting against each other.

Moderate Difficulty