The ostrich is the bird that lays the smallest egg for its size. Although it is the largest single cell in nature, an ostrich egg is less than 2 per cent of the weight of the mother. A wren’s egg, by comparison, is 13 per cent of its weight. The largest egg in comparison with the size of the bird is that of the Little Spotted kiwi. Its egg accounts for 26 per cent of its own weight.

An ostrich egg weighs as much as twenty-four hen’s eggs; to soft-boil one takes forty-five minutes. Queen Victoria tucked into one for breakfast and declared it among the best meals she had ever eaten. The largest egg laid by any animal – including the dinosaurs – belonged to the elephant bird of Madagascar, which became extinct in 1700. It was ten times the size of an ostrich egg, nine litres in volume and the equivalent of 180 chicken’s eggs.