Final answer:
Broken sea shells in the story symbolize decay and transformation, mirroring themes of change and the passage of time seen in other aspects like torn items and war. They contribute to a deeper understanding of the narrative by representing history and memories as fragments.
Step-by-step explanation:
The significance of broken sea shells in this story likely symbolizes decay, transformation, and the passage of time. Just like the sour notes from torn seams, the delayed voyage due to a shattered bottle, or the importance of a haystack with torn cloth, broken sea shells may represent something once whole that has been fractured or changed. This theme could also be reflected in the descriptions from the provided excerpts, such as buried treasures shedding light on history, a setting 'under sea' highlighting timelessness, and the destructive yet transformative forces of nature and war. These fragments can be seen as pieces of history or memory, contributing to our understanding of the past or the characters' experiences.