Animating a photographic 'object' in a clip

Here's the scene: a simple shot of a starfish on a beach shot from above.

Question: is it possible, using Motion 4, to animate the starfish so that it uses it's legs to walk?, say make an exit stage left?

I have a shot of the starfish on the beach, and a shot of the beach without the starfish.

I'm quite new to Final Cut Studio and Motion 4 so I'm not sure if it's possible to do this. I couldn't find the solution in the Motion 4 Apple Pro Training Series book I bought.

Is it possible? If so, does anyone know of a resource that could help me work it through?

Thanks guys.