 If anything is a non-actual possible object, a unicorn is. Or so it appears. But Kripke vigorously argues against such a view in the 1980 version of Kripke 1972: 24, 156–58. His argument starts with the assumption that the unicorn is (intended to be) an animal species if anything. This excludes the possibility that a horse with a horn artificially attached to its forehead is a unicorn. Kripke assumes obviously that there are actually no unicorns and that unicorns are purely mythical creatures. Also assumed is the absence in the relevant myth of any specification of the genetic structure, evolutionary history, or other potentially defining essential features of the unicorn. (Possession of a horn is not a defining essential feature of the unicorn any more than having tawny stripes is a defining feature of the tiger.) The myth describes the unicorn only in stereotypical terms: looking like a horse, having a horn protruding from its forehead, etc. Suppose that there are objects with all such stereotypical features of the unicorn. This seems perfectly possible and Kripke accepts such a possibility. But he rejects its sufficiency for establishing the possibility of unicorns. Suppose that among the objects with the stereotypical unicorn features, some have a genetic makeup, an evolutionary history, or some other potentially defining essential unicorn characteristic which is radically different from the corresponding characteristic had by the others with the same stereotypical unicorn features. Which ones among those with the stereotypical unicorn features would then be real unicorns and which ones fool’s unicorns (à la fool’s gold)? There is no fact of the matter. Given that the unicorn is an animal species, not everything that looks and behaves like a unicorn is guaranteed to be a unicorn. To be a unicorn, an object has to possess the defining essential characteristics of the unicorn. But there are no defining characteristics of the unicorn; the myth does not specify them, and the universe does not instantiate them. This surprising argument has convinced many philosophers of the impossibility of unicorns, but others have raised doubt by arguing that the notion of a biological kind, such as a species, is far more malleable than Kripke assumes (Dupré 1993).