the Romans were very superstitious. they feared the 'evil eye', the jealousy of other people. We find this in Muslim countries with the hand of Fatima, the middle finger protects from the evil eye. The middle finger is the phallic finger (expression 'fuck of... this expression comes directly from the Romans). The Phallus protected from the evil eye. Also the snake, the scorpion, the raven but also the fork, the snail, the cat etc.. as we can see on the mosaic of Antioch 'KAI SU'. Of course, this a particular meaning to the dog and the snake under the bull of Mithras...
No, I think it's not fun, but really superstition. The Romans all wore amulets, often with a phallus and a hand, even children wore them.
In the mithraeum there could be talismans
