A Compendium of Information and Images Of and Related to Christian Art and Iconography
As a symbol of heraldry the sole crane holding a stone symbolized vigilance. Legend said that cranes lived along the banks of the Nile river and were preyed upon by Pygmees. To protect themselves at night, flocks of crane would charge one bird with watch duty, and that trusted bird would hold a stone in its claws so if the bird were to neglect its duties and fall asleep, it would drop the stone, thus awakening the other birds.
Christ is often depicted as a lamb as inspired by scripture. In John 1:29, John the Baptist sees Jesus and exclaims, "Behold the Lamb of God who takes away the sins of the world." Here the Lamb of God is depicted with a cruciform nimbus and carrying a cross-bearing scepter.