 The Royal Navy banned cats and other pet animals from all ships on the ocean in 1975 on hygiene grounds; however, cats are still common on many private ships.One notable example is "Toolbox" (a feral kitten born in a toolbox), the senior ship's cat, official warrant officer and "Captain's Assistant" aboard the modern "Kalmar Nyckel".A celebrity in her own right, she is the subject of two books.