Kiwi skeleton and embryo, carved from heritage turkey feathers
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).