Has any animal ever had a rotating part?

Question

Outside of microscopic structures (I'm thinking of a flagellum, which I _think_ is a true motor) has any animal evolved a part that continually rotates compared to the rest of its body?

Answer 1

I cannot find nor think of an animal that has a body part hat continually rotates like a flagellum. The only organism that I can think of that has a constantly moving "body part" is potentially the jellyfish, with their consistently moving body / cup.