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
Bird nest bird. The flow-on consequence of this is that nest insulation is also related to parent mass. The "saucer" or "plate" nest, though superficially similar to a cup nest, has at most only a shallow depression to house the eggs. The "platform" nest is a large structure, often many times the size of the (typically large) bird which has built it. Depending on the species, these nests can be on the ground or elevated. In the case of raptor nests, or "eyries" (also spelt "aerie"), these are often used for many years, with new material added each breeding season. In some