why is there a 3d grid on my artwork?

I have a pdf that is grainy. It is set as a background layer in illustrator and I am drawing new vector objects on top of it to rebuild it. For some reason, a blue, orange and green grid appears in the middle of the artboard (which looks like it is a x,y,z axis grid). There is also a circle in the upper left corner with a 3 sided cube in it which floats above the layers that I add. This circle has a small 'x' in the corner, which looks like it would close the element but it does nothing. How do I remove these two things?