There are some marvellous [fish] which lift themselves out of the water and fly for quite a long time like butterflies, but I don't know how long they can stay in the air. I asked experienced sailors about this, wanting to know where the fish came from. They replied that in England and Ireland very beautiful trees grow on the shore bearing fruit like apples. In these apples, worms are born, and when the apples are ripe and fall they break open and the worms fly away because they have wings like bees. If they touch first on land they become airborne and fly with other birds. If they touch first at sea they become sea creatures and swim like fish but from time to time they also use their natural ability to fly.
Perhaps wisely, Ludolph remarked that he wasn't sure if trees like this really existed but he recorded what he'd been told'.
- Quoted in Susan Rose, The Medieval Sea, London, 2007