Dolphins and other marine mammals have no outer ear, but they also have the ability to hear sounds. To date we did not know how dolphins carried sound from the surface to the ears of the head, but some researchers at the Massachusetts Oceanographic Institute have just unraveled the mystery of this ability: it seems they use maxillofacial fats as sound transporters.
Using MRI and CT scans, maxillary fats and ear tubes have been shown to be trumpet shaped and through them dolphins carry the sound to the inner ears