Breath goes out with the sound Ha and enters again with the sound Sa. So simple. So natural. So freeing. The living being is indeed always repeating the mantra Ham-Sa, the seed of the Universe, the breath of life (prana-bija). Its visual symbol is the Hamsa, the royal mallard, celestial swan, who is the vahana of Brahma, the creator.
In the Rig Veda, it is the bird which is able to separate Soma from water, when mixed; in later Indian literature, the bird separates milk from water when mixed. In Indian philosophical literature, Hamsa represents the individual soul or spirit, or the universal soul or supreme spirit.
In numberless passages of Indian thought, it is emphasised that the Hamsa is white. We're forgiving ourselves for taking artistic liberties on this one, don't be mad!