I usually rotate between two shells throughout the day - as I change one I hang up that shell incase it has any moisture on it, while using another... Next diaper change I'd go back to the first shell, snap in an insert and we're good to go. (diaperjunction.com)
Natural selection is generally believed to have favored larger size, and consequently the need for hard skeletons to provide structural support - hence, the Cambrian gave rise to the first shelled animals and animals with exoskeletons (e.g., the trilobites). (fossilmuseum.net)
Aside from understanding the labels, you'll know the difference as soon as you crack the first shell — the yolks will be a rich, vibrant golden color and have tons of flavor rather than being a pale, flavorless yellow. (holisticsquid.com)