Groups of nine deities, nine being the plural of three (in Egypt the number three symbolized plurality in general) but some enneads had more than nine gods. The earliest and principal ennead was the Great Ennead of Heliopolis. This was headed by the sun god and creator Re or Re-Atum followed by Shu and Tefnut deities of air and moisture; Geb and Nut who represented earth and sky; and Osiris Isis Seth and Nephthys. Enneads are associated with several major cult centers.