Egg tray has a dimpled form in which each dimple accommodates an individual egg and isolates that egg from eggs in adjacent dimples. This structure helps protect eggs against stresses exerted during transportation and storage by absorbing a lot of shock and limiting the incidents of fracture to the fragile egg shells. An egg tray can be made of various materials, but this kind is manufactured from molded pulp

Reference: An egg tray can be made of various materials, foamed plastics such as polystyrene foam, clear plastic or may be manufactured from recycled paper and molded pulp by means of a mechanized papier-mâché process