Military button?

[Zachbl92]

So, it's either C S with what looks to be a anchor in the middle or O S? It was a 2 piece and the back is gone... also could be s f o maybe?
Regular button or....?
Any information is appreciated.
Thanks,
Zach

 

[fyrffytr1]

I don't have any idea but I took the liberty of trying to enhance your photo for others to see. I hope you don't mind. Also, can you post a picture of the other side even if the back is missing.