Egg embryo is adequately developed it hatches, i.e. breaks out of the egg's shell. Some embryos have a temporary egg tooth they use to crack, pip, or break the eggshell or covering. The largest recorded egg is from a whale shark, and was in size. Whale shark eggs typically hatch within the mother. At and up to , the ostrich egg is the largest egg of any living bird, though the extinct elephant bird and some dinosaurs laid larger eggs. The bee hummingbird produces the smallest known bird egg, which weighs half of a gram (around 0.02 oz). Some eggs laid
Eurasian dotterel It nests in a bare scrape on the ground and lays two to four eggs. The male does the incubation and rears the chicks, the female having gone off to find another male and lay another clutch of eggs. It is a common bird with a wide range and the International Union for Conservation of Nature has rated it as being of "least concern". The English name dates from 1440 when it was used to refer to the bird and also as an insult for someone considered simple or a dotard. It is not clear which use is the oldest,