During the Middle Ages Muslim and Jewish scholars could not determine if various birds such as geese and Puffins were fish or or humans and hence called for them to be killed—warning not to eat them as they were creatures of unknown origin. Since they did not know if they were fish or flesh, they also argued on which method would be best to kill these birds.
The puffin was often mistaken for the little auk and was often referred to as ‘half fish, half flesh.’ ((Tate, Peter (2008). Flights of Fancy: Birds in Myth, Legend and Superstition. New York, NY: Delacorte Press.))