So there is a bird called a Barnacle Goose
and a crustacean called a Gooseneck Barnacle
And because bird migration wasn't well understood by Western scholars, a number of them decided that since they'd never seen an egg or nest, obviously these geese grew from barnacles.
Here's Gerald of Wales (1146-1223), pure makin' shit up:
"I have often seen with my own eyes more than a thousand minute embryos of birds of this species on the seashore, hanging from one piece of timber, covered with shells, and, already formed."
the Barnacle Goose was considered a fish for the purposes of Catholic fasting until 1215.
HOWEVER then we have Holy Roman Emperor Frederick II (1194–1250) entering the ring with a steel chair in the form of the following quote:
"There is also a small species known as the barnacle goose...There is however a curious popular tradition that they spring from dead trees. It is said that in the far north old ships are found in whose rotting hulls a worm is born that develops into the barnacle goose. This goose hangs from dead wood by its beak until it is old and strong enough to fly. We have made prolonged research into the origin and truth of this legend and even sent special envoys to the north with order to bring back specimens of these mythical timbers for our inspection. When we examined them we did observe shell-like formations clinging to the rotten wood, but these bore no resemblance to any avian body. We therefor doubt the truth of this legend in the absence of corroborative evidence"
In spite of Fred's good science, a variety of scholars continued to reference the goose-barnacle hybrid until the 1500s.
The whole Wikipedia article is gold. See also the Vegetable Lamb of Tartary.
