Among the powers worshipped in On (Heliopolis) was the benu-bird, described in the Pyramid texts as a kind of wagtail, but depicted as a heron from the Middle Kingdom on. The name 'benu' probably comes from the verb 'weben', 'to rise', from which the word 'benben' is also derived. The name refers to the association of this bird with the being that appeared on the newly created land at the beginning of creation. Through its link with primeval times, it was given the designation 'he who is created of himself', and could be regarded as a manifestation of the primeval/creator god himself. Thus Atum apparently appeared in the shape of a benu-bird in the benben-house during creation.
Besides being connected with Re, the benu-bird was also linked with Osiris from the Coffin Texts on; it is a manifestation of Osiris or the ba of Osiris that 'came out of the heart of Osiris'. Through this association, the benu-bird can also be found on heart scarabs.
A connection seems to have been perceived between the benu-heron and the ba-bird. In the Coffin Texts, unhindered passage through the Underworld is linked with the benu-bird, and in the Book of the Dead, the benu-bird is one of the forms that the deceased hopes to assume - through its association with the ba, it guarantees the deceased the ability to transform himself. In the Late Period, the benu-bird was even used as a letter for the ba and became a symbol for life renewing itself after death. This is the meaning that was adopted by the Greeks and Christian Church Fathers. Although there are many elements in the later phoenix legends that cannot be found in the Egyptian sources, they could have an Egyptian background, for example, the death of the phoenix in the flames evokes the appearance of the bird in the light of the rising sun, and the periodic return of the phoenix, which according to Tacitus follows the Sothic cycle, is reminiscent of the close connection the benu-bird in Egypt had with time, eternity and regeneration.
The main benu-bird cult centre was at Heliopolis, but there were others elsewhere in Egypt; for example, a 'large benu' was worshipped at Heracleopolis, and there was also a benu cult at Edfu. The link between the benu-bird and the great gods Atum, Re and Osiris certainly played a role in the spread of the cult.