Countermark

https://rpc.ashmus.ox.ac.uk/countermark/284 
GIC 155
laureate head l.
circular 
9 mm 
Sometimes on reverse. They may have been applied at Neapolis (Samaria), but the provenances of GIC 408, with one example paired with GIC 155, give some reason to doubt Neapolis 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC II, 2218 Show 2218 16 2
Show 229
Show 200
Show 192
Show 163
RPC I, 4309 Show 4309 11 1
RPC I, 3869 Show 3869 22 1