Help with Identification (Byzantine?)

Got this coin but it's pretty busted and I'm having a hard time identifying it, if it's even possible at this state. 

It's about 25mm at it's widest.

I think you got it spot on, probably byzantine, I can tell (if I’m correct) the “M” looking thing in the first picture and the cross, as for the exact coin… I’m still looking :)

Look to Arab-Byzantine (square coins)

THE DESIGN, AS BAD AS IT IS, MAY BE 5TH CENTURY OR LATER. tHE ARAB IDEA IS A GOOD ONE.

It is either a byzantine follis of Constans II or an imitation thereof, aka Arab-Byzantine. It has been cut at one point and standard identifying marks are long gone, but if I had to take a guess, it's probably SB-1005. Not worth the time or effort as you can get better specimens dirt cheap…