The ankh is an ancient Egyptian symbol of life.
Some have speculated that it represents a stylised womb. It does bear a strikung resemblance to the symbol used to represent the Roman goddess Venus which is now so familiarly used to identify the female sex. (This is how I link the Ankh to the male (Mars) symbol in my cycle.)
Early Coptic Christians adopted the Ankh as a form of the cross known as the crux ansata.