Looks like it's cracked. Did it get dropped or have something dropped on it? Or hang out with some hard object in a pocket or bag or get accidentally banged into something?
Here's a picture of my cases. I'm missing my one that has a wood back with a carved ocean wave scene on it... Just recently got it but misplaced . Also have another clear case that's a little beat up so it didn't make the photo shoot. lol.