According to many legends, from more then a few cultures worldwide, it is an animal that is born when you are (as a spirit) it's job is to protect and guide you through life. Now determining what your animal is varies way too much for me to get into here. Like I said many cultures are different.
A Draconequus.
http://youtu.be/boj75h3urLU
Uniwhatever = Magical Horn
Pegawhatever = Wings
Aliwhatever = Both
My old account is just*shrugs*