An animal was slaughtered and in her womb was a fetus in the shape of a dove. The dove is forbidden for consumption because it has no hooves, which is the sign permitting animals for consumption.
One of the sages, Rav Ada the son of Ahava, asked another sage, Abaye: An animal slaughtered and in her womb was found a fetus in the shape of a man. Is this fetus permitted for consumption? What are the issues under debate? On one hand, the fetus takes after its mother, and just as the bovine mother is permissible for consumption, so the fetus — even if it has the shape of a human. A human shape, though, is not like a dove’s shape, for the dove has no hooves or feet at all. On the other hand, in the final analysis it does not have the shape of an animal, it has the shape of a man, and one may not consume people. As ruled in Halacha, just as if one finds a dove in the womb of a cow after the cow has been slaughtered, one is forbidden to consume the bird, so one is forbidden to eat a fetus shaped like a human. (The Talmud did not rule on this issue.)
(Babylonian Talmud Tractate Niddah 23b)