Largest organisms is frequently poorly documented and many are subject to conjecture and estimation. The largest living bird, a member of the Struthioniformes, is the common ostrich ("Struthio camelus"), from the plains of Africa and Arabia. A large male ostrich can reach a height of and weigh over . A mass of has been cited for the common ostrich but no wild ostriches of this weight have been verified. Eggs laid by the ostrich can weigh and are the largest eggs in the world today. The largest bird in the fossil record may be the extinct elephant birds ("Aepyornis") of Madagascar, which
Bird egg 7500 pores. The shape of eggs varies considerably across bird species, ranging from near-spherical (such as those of the little bee-eater) to highly pyriform or conical (such as those of the common murre) with the familiar shape of the chicken egg lying in between. Early scientific investigators of egg shape suggested that the oval shape of eggs was caused by the egg being forced through the oviduct by peristalsis. In this often-repeated but incorrect theory of egg shape formation, the contraction and relaxation of the muscles which push the egg down the oviduct cause the spherical egg membrane to distort