Think you nailed it @stevex6 ! My snake has a beard, with some fins or something on his head and they just happen to be close to the letters.
That's because he's wearing a lion-skin headdress and you're used to seeing Commodus with a laureate portrait.
It's actually supposed to be a beard, even though snakes don't really have one. This page discusses this issue briefly.
Here is a sestertius of Commodus showing Hercules o the reverse. The man just loved that club! Commodus. AD 177-192. Æ Sestertius. Rome mint. Struck AD 183. Obv: Laureate head right Rev: Hercules standing right, holding bow and lion’s skin, leaning on club resting on ground. RIC III 365. The picture is not good.
I thought the same thing about the ear at first and suspected some tooling going on. After googling and looking at some more images of this type, it looks more like the headdress frames the ear in a funny way that ends up looking like this after some wear. Cool coin, @ro1974!