Countermark

https://rpc.ashmus.ox.ac.uk/countermark/321 
GIC 194
gorgoneion?
square 
P. Seyrig 76 coin of Claudius with GIC 342 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC III, 3403 Show 3403 5 3
RPC III, 3403 Show 3403 2 3