Headscratchers / The Little Mermaid

See here for the Disney movie.

Anime version

At the end of the movie, Marina sets her pearl hair pin on the ship's balustrade, as a parting gift to the prince, along with a green scale, just like the one she plucked from herself to lay on his wound in the beginning. Where on earth did she get this? We're never shown any scene that could explain this random scale being in her possession after her transformation.