Flying boar

The flying boar is the symbol of the Beifong family. It is first seen in the Foggy Swamp, where Aang envisioned a flying boar next to a laughing girl while separated from the rest of the group. The vision ultimately led to Team Avatar finding Toph in the Beifong estate.

Anatomy
The flying boar appears as a wild boar with wings. It is seen to have light colored skin with white wings. It is presumed that the flying boar is hairless, or very short haired.

Place in the World of Avatar
Though a flying boar is never actually shown, it is possible they exist, as many different types of boar are shown in the Earth Kingdom. It is possible that the flying boar is merely another hybrid between a boar and another animal. However, when the group mentions a flying boar to the Earth Kingdom boys they meet, the boys can only think of the Beifong family instead of saying it is just a common animal, suggesting that it is either very rare or mythological.