They are used in the novel Lord of the Flies to show the deterioration and destruction of the boys society and rules.
Piggy's glasses symbolize civilization and when they are broken it symbolizes the destruction of the civilization the boys had at the begining of the book. The conch represents order between the boys and how they could not speak out of turn if the didn't have the conch. When the conch is broken it represents the end of their order.
