20 cm Translucent Microderoceras ammonite bed, from Charmouth beach

A very special piece with multiple Microderoceras, Cymbites and Promicroceras ammonites measuring 20 cm across, including the matrix. The back has been worn by the sea and then ground down in the workshop to to allow light to shine through the ammonites. Showing the brilliant colours of the calcite that the ammonites are preserved in.
 
Some minor repair to the reverse to reinforce the back - no restorations, 
The piece originates from the Birchi nodule bed. 
 
Lower Sinemurian, Black Ven Mudstone Member, Charmouth Mudstone Formation, Charmouth, Dorset. 195 MYA