How can I animate the surface of a 3D object?

I have a sphere, with it's material being a smiley face PNG. I've created multiple PNG files that can make up a blinking animation, but animating the 3D sphere isn't as simple as using PNG files to animate a 2D object which I've done before, how would I go about animating the surface of the sphere?

I could think of a way to do it in a script but I was wondering if there were any components that would help me with this?