Countermark

https://rpc.ashmus.ox.ac.uk/countermark/480 
GIC 360
murex shell (rectangular punch)
rectangular 
5 x 4 mm 
 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC II, 2065 Show 2065 2 2
RPC II, 2066 Show 2066 6 2