Lmao

Both in real life and fiction. I don't understand why they are so common in mangas anyways. Experienced people are much more fun to read about.

The comb jelly—also known as the warty comb jelly, sea walnut, or Mnemiopsis leidyi—has a disappearing butt. Sidney Tamm of the Marine Biological Laboratory in Woods Hole, Massachusetts, told New Scientist that "there is no documentation of a transient anus in any other animals that I know of. It is not visible when the animal is not pooping. There's no trace under the microscope. It's invisible to me."