Howdy y'all,
I was wondering if you could please help me to identify these skulls that I found in my cat's outdoor house today. I'm not positive that they are skulls, but I just guessed that because it looks like they have eye sockets and nasal openings on the sides. Plus I have no idea what bone it might be if it's not a skull.

That styrofoam plate is a standard sized 8" plate.







I'm in IL near Chicago. Thanks!