The Ziz is a rabbinic creature rather than a biblical one, constructed out of a single obscure expression. Psalm 50:11 speaks of the ziz sadai, usually translated "the moving things of the field" or "the wild beasts," but read by later midrashic writers as the proper name of a colossal bird, so vast that when it stands in the sea the water reaches only its ankles, and its wings can eclipse the sun. It completes a symmetrical scheme: Leviathan rules the deep, Behemoth the dry land, and the Ziz the air, the three great creatures of sea, earth and sky formed at creation and kept for the messianic banquet. The Ziz is the least developed of the three, appearing mainly in aggadic elaboration rather than in narrative, and it illustrates a characteristic rabbinic move: an unfamiliar scriptural word is taken as the trace of a hidden marvel, and a whole creature is inferred to fill the gap.