Countermark

https://rpc.ashmus.ox.ac.uk/countermark/475 
GIC 355
crab
circular 
4.5 mm 
Certain cities used a crab motif on their coins including Mopsus, Mylasa, Cos, Gabala. It was also a sign of the Zodiac. 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC I, 1656 Show 1656 64 1
RPC I, 1656 Show 1656 98 1
RPC I, 1656 Show 1656 103 1
RPC I, 1656 Show 1656 107 1
RPC I, 1656 Show 1656 131 1
RPC I, 1656 Show 1656 136 1
RPC I, 1656 Show 1656 139 1