Need Help Identifying This Ancient Nummus, Follis, Ae4?

I was on a real roll tonight, identifying old, worn-out coins in my grandfather's collection until I came to this one. I can't seem to break through: is it Roman, Greek, copper, bronze... is it even real?

What I can tell you for a fact is its diameter, 15mm and mass, 1.29 grams.

What do you think?




P.S. In better light, there are three lines of print on the reverse: the first line looks like a V O S, the next line looks like a W and the last line looks like it begins with M V. But I wouldn't swear to any of these.