Lemmings don't jump over cliffs in reckless group suicide. It's a myth.
I referred to lemmings when describing a mass self-annihilation movement in a short story. The story was rejected, the editor pointing out my metaphor was wrong: Lemmings don't commit suicide.
Considering I'd put dolphins in the role of psy-villains, I think my myth-take with lemmings was the least of the story's problems.