A brief overview:

The fascinum (or phallus or Divine Penis) was a cult like object. It was used to ward off evil (the evil eye) and for protection, versus something sexual as one may think. It was celebrated, worshiped, and its likeness was used in celebrations. It has been found depicted on rings, pendants, wind chimes, and buildings (often thought to be brothels but more likely to protect the residents of the home). Carvings were also found in places of possible danger such as on street corners and bridges. They were also placed on the front of carriages and possibly worn by soldiers for presumably the same reason. Rings and pendants were worn by boys (sometimes even bestowed on them at birth) to protect their health and virility. Overall, the fascinum, when worn especially, was believed to be a powerful form of apotropaic magic. Given its prevalence it was obviously an important part of Roman society. It can be surmised that the reason it has been omitted from modern literature is due to its modern taboo nature. Luckily its importance and meaning can be found in cultural, religious, and archaeological finds. So, if you’re worried about the evil eye…