Parrot Eggs

Just as parrots form a unique order of birds - psittaciformes - with only the most conjectural relationship to other avian groups, so have their eggs proved exceptional. The most striking difference is in the resistance the shell has against injury.
Other birds' eggs are more brittle.
A strong tap will chip them and the sharp edges of the pieces, as they are depressed with the blow, too readily cut through the egg membranes. When the albumen leaks out, or if air gets to lie under the inner-shell membrane, the embryo dies. The unique "spongy" structure of the proportionately thinner parrot egg shell gives it a greater pliability. A similar slight blow merely caves in a mild dent at whose edges the shell membranes hold firm. In practical terms this means that the psittaculturist can give first-aid repairs applying, say, a wipe of nail varnish, to a dented parrot egg with some likely success of it hatching.