Koala sheep

Koala sheep are the main inhabitants of the Black Cliffs. They are extremely docile and seem to spend most of their days eating grass, sleeping, and avoiding their natural predator, the boarcupine. They care very little about their surroundings and are in no way afraid or intimidated by humans, even to the point they apparently do not mind being used as pillows. Their wool is very soft and, if shaved off, can create an exceptionally comfortable cushioning.

Uses
Aang was told to pick up a specimen and scream into its fur in order to aid in relieving stress, as well as being made to lie down on it as previously mentioned, though both applications failed to cure the Avatar of his chronic insomnia. In the end, Team Avatar sheared several koala sheep and used their collective wool to create a makeshift cot for Aang to sleep on, which he was finally successful in achieving.

Anatomy
Koala sheep have the woolly bodies of sheep and the ears, feet, and faces of koalas.

Connection
Koala sheep are clearly a cross between their namesakes. The fact that they like to spend most of their time eating and sleeping is a clear connection to the real life koala, as these creatures are only awake for five hours and spend about three of those eating.