Large Ammonite Aptychus - Unknown Location
Large Ammonite Aptychus, and partial ammonites - Unknown Location / age
Aptychi come as symmetrical pairs, therefore, this represents one side of the pair. They are now considered to be either a jaw piece or a two-valved closing hatch.
The aptychus is very large size at 5 cm (max diameter). The matrix is 11 cm x 9 cm x 3 cm