Sadly have not had the leisure to work with Unity for a while now :( That said, I suspect you will want ot import it first into a 3d tool (such as blender) and do a bit of work on the model before importing it into Unity - maybe set some default flat textures on the faces for example, then save in a more Unity friendly format (it used to support Blender out of the box way back when - not sure if it still does?)