"Totally random and not at all theory-related comments: my latest favorite totally-unproven theory is that dolphins communicate in 3D, by emulating sonar signals."

This was the basis of a science fiction novel called "A Deeper Sea," by Jablokov. It's explored in much detail. Jablokov did superb homework, better than I've ever seen in sci-fi. Kind of reactionary to romanticism, though... which turned me off even as I understood that it was necessary to treat the subject matter accurately.