Seems an egg eater has access to an egg after it is laid.
She doesn't know how long it was sitting in the nest.
Common reasons for chickens to eat their own eggs include:
Hard, solid floors. Research shows that egg layers who are raised in cages are generally less apt to eat their own eggs.
Overcrowding. If you don’t give your layer hens enough room in your backyard coop, the stress may provoke them into habits such as egg-eating.
Poor nesting space. If the nests you provide your hens are too small, or if there aren’t enough nests for your backyard chickens to share, the stress may provoke egg-eating and other poor habits.
Nutritional deficiencies. Farming research suggests that nutritional imbalances, specifically as it relates to vitamin D and calcium, may provoke egg-eating in layer hens.
Hope this helps.