What is the name given to the mass of adipose tissue (body fat) found in the forehead of all toothed whales?

The melon is a mass of adipose tissue (body fat) found in the forehead of all toothed whales. It focuses and modulates the animal's vocalizations and acts as a sound lens. It is thus a key organ involved in communication and echolocation.

The melon is structurally part of the nasal apparatus and comprises most of the mass tissue between the blowhole and the tip of the snout. The function of the melon is not completely understood, but scientists believe it is a bioacoustic component, providing a means of focusing sounds used in echolocation as well as creating a similarity between characteristics of its tissue and the surrounding water so that acoustic energy can flow out of the head and into the environment with the least loss of energy.

In the past, some scientists believed that the melon had functions in deep diving and buoyancy, but these ideas have been discounted over the last 40 years and are no longer considered valid by cetologists.