A single large Microderoceras ammonite (around 140mm diam) just revealed on the edge of the block.  Does have a little calcite veining and a hint of pyrite oxidation (although looking at it this is just superficial and shouldn't affect the calcite). 

1 edge slightly missing but the majority of the ammonite should be here. It's possible that the centre is crushed which is common with these ammonites. The outer coil can be 3D, but this is less likely with the centres. 

A reasonable amount of overburden to remove. With Birchi nodules it is recommended to remove as much matrix as possible.

Difficult