This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Orphan Bird (Medieval Bestiaries)
The Orphan Bird (also known as the Orphanay or Rafanay) is a legendary bird from medieval bestiaries. It had a peacock's neck, an eagle's beak, a swan's feet, and a crane's body. It would lay its eggs in the sea. The good eggs would float, while the bad eggs would sink.
The mother can tell which eggs hold the best chicks: the good eggs float a little below the mother, while the bad ones sink to the sand at the bottom of the sea. When it is time for the eggs to hatch, the good ones rise up under the mother's wings, where the chick come joyfully forth and are led to their father. The bad eggs hatch where they are, at the bottom of the sea, and the young birds must live there in darkness and grief.