The key of Life
The ankh is an ancient Egyptian hieroglyphic symbol that was most commonly used in writing and in art to represent the word for "life" and, by extension, as a symbol of life itself. Its use continued through the Coptic Egyptians who adapted it as the crux ansata, the christian cross is a variant of the ankh.
The sign has a cross shape but with an oval loop in place of an upper bar. The origins of the symbol are not known, although many hypotheses have been proposed. It was used in writing as a triliteral sign, representing a sequence of three consonants. This sequence was found in several Egyptian words, including the words meaning "mirror", "floral bouquet", and "life". In art the symbol often appeared as a physical object representing either life or substances such as air or water that are related to it. It was especially commonly held in the hands of deities, or being given by them to the pharaoh, to represent their power to sustain life and to revive human souls in the afterlife.