Is this a rabbit or a duck?
The 124 year-old drawing first appeared in a German magazine in 1892 under the title "Kaninchen and Ente" – Rabbit and Duck.
According to The Mirror, children who saw the picture at Easter were more likely to see a rabbit, but in October duck was a more frequent answer.
It has also been seen as a test of creativity.
Dr. Joseph Jastrow, who studied optical illusions, noted in 1899 that if you can flip quickly between the two animals, that means you're creative.
So what do you see? Take our poll below and let us know.