It's definitely a Siscia mintmark, as I tilt it in the light I can make that out quite clearly. The reverse I have found but I've searched hundreds of images of the obverse and can't find it. All the coins I'm seeing, the ear is visible but on this coin there is no ear. There is a flap running near to the tassels which goes over the ear. It looks to be a type of helmet with flap or it is a large piece of jewellery?























