What adaptation successful for development is characteristic of all embryos?

A key adaptation common to all embryos is the presence of a protective structure, such as the amniotic sac in mammals or the egg membrane in reptiles and birds, which provides a controlled environment for development. This adaptation helps to safeguard the developing embryo from physical damage and desiccation, while also allowing for the exchange of gases and nutrients. Additionally, the ability to undergo cellular differentiation enables embryos to develop specialized tissues and organs necessary for survival after birth or hatching.