Mac Excel really doesn't support Object Linking & Embedding [OLE]... In fact, object links aren't supported at all. Has the file been edited on a Windows box?
Have you tried using Edit> Find> Go To - (Special) - Objects?
Also, if you can select an object [even if you have to insert a shape/picture] you may have success with the Selection Pane on the Shape Format contextual tab.
Another option is to select one object then repeatedly press Tab to jump from one to the next.