Kiwi (Apteryx, gr. "Wingless") is a timid animal, a nocturnal bird with a peculiar appearance. The size of a hen, and a highly developed sense of smell, the kiwi has two peculiarities that make it unique in the world.
1 - The first peculiarity is its appearance, in fact, at first thought it was a mammal. Why? Because instead of feathers, has bristles (albeit soft). It has large nostrils in its beak, and has hollow bones like most birds. So the Kiwi is the heaviest bird (in proportion), their legs are strong and running and defend views closely resemble cassowaries ... but that is the second peculiarity.
2 - Evolutionarily speaking, the animal closest to the Kiwi, is the Moa. The Moa is
considered the largest bird that ever lived, in fact, was called "elephant bird" and lived until about 100 years until the man finished with the species.
Instead, the Kiwi is not larger than a hen. But the egg is not that of a hen. It is said that the egg of the Kiwi is huge, bigger than himself ... but of course that's impossible ... but only just ... and is in proportion to the animal body with a large egg
throughout the animal world. In fact, during pregnancy, much of the body size is to accommodate a huge egg. But look at the x-ray.
Indeed, the left image shows the Kiwi again laid the egg. It will have been rested.