Hi I have come across this very old coin, possibly Roman coin? Sorry not much detail on the photos, so this may be a challenge to work out!
Yes it is a Late Roman Bronze coin. With the SECVRITAS REPVBLICAE reverse and the shortish legend I can make out on the obverse, I'm going to guess that it is from the emperor Valens.
Valens. A.D. 364-378. D N VALEN-S P F AVG, diademed, draped and cuirassed bust of Valens right / SECVRITAS REIPVBLICAE, Victory advancing left, holding wreath and palm I can't quite make out the mintmark, but your coin is either from Arles or Lyon and I am thinking Lyon, like below but I believe I can see a dot at the end of your mintmark
Unfortunately, in that condition, it is basically a slug. I get ones like this in uncleaned lots I occasionally buy. Less than a dollar a piece. Still an interesting piece of history.