The Da Vinci Notebooks
This creature, when the moon is full opens itself wide, and when the crab looks in he throws in a piece of rock or seaweed and the oyster cannot close again, whereby it serves for food to that crab. This is what happens to him who opens his mouth to tell his secret. He becomes the prey of the treacherous hearer.
All snakes flie from this creature; but the weasel attacks it by means of rue and kills it.
This carries instantaneous death in its fangs; and, that it may not hear the charmer it stops its ears with its tail.