The Kiwi bears the largest egg of any bird in relation to its body size. The equivalent for us would be to give birth to a four-year-old. The bird usually lays two eggs. For the lower egg containing the embryo, I couldn’t find any illustrations of a Kiwi embryo so I made some assumptions which may be wrong—taking out the developing wings (adult Kiwi wings are about the size of the tip of your pinky finger).