A heron. Specifically, Ardea bennuides a heron from Egypt and the Arabian peninsula that is now extinct. Descriptions of the bird, including Egyptian drawings, show the bird to look much like the Great Blue Heron of the Americas. (see picture) The bird, like most herons dwelled in shallow waters and water laden plant beds hunting for fish, frogs and other small animals. It is also believed, that like modern herons that inhabit areas where humans fish, these birds followed fisherman and may even have been tamed by them. (If you're curious about the pterodactyl comment check out the call of the Great Blue Heron on What Bird.com.)
So what does this all have to do with Ancient Egypt?
The Benu Bird was a heron (Ardea Bennuides, hence the scientific name containing Bennu) that the Egyptians associated with the sun. It wasn't just the sun but it was the closest thing the Ancient Egyptian mythology has to what we might call a phoenix. Benu served many purposes in the religion. He was the bird whose screaming call started time. He was the bird who set Ra on fire to blaze in the sky. Benu was a symbol of rebirth and rejuvenation. In the later periods he was merged with the idea of the Arabian phoenix. He also accompanied Ra in the boat through the Duat. In some myths he lights the way for the boat and in others he is referred to as the Ba (soul) of Ra.
One of the most important myths associated with the Benu Bird is related to creation. This myth is most often recorded in Helopolis (modern Ain Shams .."Eye of the Sun" just north of Cairo) Even Herodotus wrote about the Benu Bird. It is from his retelling that we get the association between Benu and the phoenix.
At the beginning of time (sometimes before Ra exists) Benu rises from the waters of Nun. He brings and creates light to drive away the chaos. Benu, meaning "Brilliant Rising" or "Rising Light" is the name Nun and/or Ra bestow upon him. Benu then cries out and time starts. The bird then leaves Egypt but it is never quite told where he goes. Herodotus claims in his version that he flew off to Arabia. In his version after 500,000 years the Benu returns. Ra does not recognize the bird because he did not create him. The bird informs Ra that it is the child of the first Benu and in a bundle carries the remains of its father. The Benu wishes to bury its father in the mound of creation where he first rose from chaos. Benu then flies off and is supposed to return when Osiris becomes pharoah.
Other examples of the story of the Benu Bird exist in the Book of the Dead (ie the Book of Coming Forth by Day) and some of the various coffin texts. Here he serves the purpose of guiding the gods through the Duat. It was believed since Benu appeared from the darkness as the first light he was best suited to navigating the darkness of the Duat.
Benu's name is related to the Egyptian verb "webenu" (wbn) which means "to shine" or "to radiate light". Some of the titles associated with him were "Lord of Time", "He Who Brought Himself into Being", "The Shining One", "Dispeller of Chaos", and "He Who Keeps Time". Benu is sometimes associated with Thoth because Thoth recorded history and Benu kept track of time.
|From the Tomb of Inherkha|
Benu was worshiped for many reasons. He was believed to be associated with safe travel, both in the Duat and at night. Benu was a sign of luck and rejuvenation. Many texts associate Benu with the rising of the Nile which might have to do with the heron species migrating to Egypt when the Nile is rising and there is plenty of floodplain to hunt in while raising chicks.
Books to check out:
**Cry of the Benu Bird: An Egyptian Creation Myth by Shana Greger
**Egyptian Mythology: A Guide to the Gods, Goddesses, and Traditions of Ancient Egypt by Geraldine Pinch
**The Egyptian Book of the Dead. (There are many, many, many versions of this book. I personally prefer the version by Faulkner because it is easy to understand and has nice pictures of the complete text.)