An item that stands for more in a story than it usually does elsewhere is an example of symbolism.
Symbolism refers to the literary element which is used to represent something else. In order to create emotion or mood, this figure of speech is used by the author. It represents something through the use of a person, an object, word or situation.
Common types of symbolism are allegory and metaphor.
A metaphor is a figure of speech which describes an object or action that isn’t literal in its sense, but it helps in creating a comparison to explain an idea. It states the one thing to be another because they are the same in characteristics.
Allegory are in concrete form, from the personification of abstract concepts.