The anima first appears in an animal skin, either as a fish or a mermaid, or, most frequently, as a bird, and then she turns into a human being. Generally her lover keeps her former animal skin or bird garment in a drawer.
Von Franz establishes the animal skin as the archetypal container of anima identity in fairy tales, a liminal garment whose preservation or destruction determines whether psychic transformation succeeds or collapses.
, The Interpretation of Fairy Tales, 1970thesis