.. in order to use in augmented reality application on iphone?

I have an app working like that; camera detects the marker and then it places an object related to that marker. However the object is not animated. It stands there. Of course i can move the object programmatically but i don't want to do that. What i want is the object has animation itself. I searched but i can't find exact file format. There are .obj files (not animated itself, is it true?), .mtl files, .anm files .etc. If the format is one of them, then can you give me an example model?

Thanks