Easter-egg In Gavel?

So today i was grinding in the light forest in gavel and i found a cave
There were grifforion anaplis and grifforion scouris excuse me if the names are wrong XD
and then i went further and i found this big cirkel thing with two lettres on it.
If you translate the lettres you get an I and an F on the two sides.

I can't post the links of the foto's tho :(

I don't know what it is or if it already has been found but i thought it was a fun little easter-egg.
If you guys know more about it let me know ;3

 

Pretty sure this was found before, I recall finding something like this myself. Good job on finding this though!

 

I honestly don't go looking for easter eggs. I probably pass by them all the time. Good job though.