Behemoth, Leviathan.....but where is Ziz

there are song after song, album titles after album titles, band name after band name, influenced by these two ancient beasts/animals, the ruler of the earth and the ruler of the sea, they are the pure image of nature, of elements of the old, the benevolent., the unreachable, the untamable.

But as well fared they seem to be in old Abrahamic myths and folk lore, they seem to forget that it is a TRIPOD, which all mythologies have. a threefold share of power and destruction and balance after all. balance is one red line in every belief system, balance of power and structure, these bands seem to forget or not aware of this third animal the third ancient beast form a time which is unknown to us, the mighty Ziz, da ruler of the sky, the giant bird. the creator of storms and mists, the negotiator, the traveler, while Behemoth is the embodiment of hunger, of mother earth itself, Leviathan lead a path of destruction and havoc, swallowed ships, flooded cities and he�s moth led straight to hell,

Why is Ziz forgotten in music by these so called metal musicians/nerds? When they at first want to look like they have read a thousand of books (i haven�t neither done so)? i would expect they would also draw from images from Ziz   

The ziz has another name, Renanim, because he is the celestial singer. On account of his relation to the heavenly regions he is also called Sekwi, the seer, and, besides, he is called "son of the nest," because his fledgling birds break away from the shell without being hatched by the mother bird; they spring directly from the nest, as it were. Like leviathan, so ziz is a delicacy to be served to the pious at the end of time, to compensate them for the privations which abstaining from the unclean fowls imposed upon them.