In the novel, Lord of the Flies, the boys landed on an island during a war when their plane crashed. As the students began to gather together, and coming from the British system of schooling where students with leadership qualities are the recognized leaders, they needed to find ways to organize themselves. The two leaders who emerged are Ralph, a boy with natural leadership skills, and Jack, the leader of the choir boys.
Piggy proposed the conch as the symbol of authority and the boys agreed. They all agreed to use the conch instead of something else because the conch was easy to hold, easy to pass to another student, easily seen and thus the perfect object to be the symbol of authority. Whichever student had the conch was the only one who could speak at the time while the other students were silent and listening.
Something had to be used so that the boys understood that, for the moment, someone else was speaking and in charge, and they needed the order the conch produced. So the main purpose of the conch was to produce order. The conch thus made the world at the beginning seem more normal and more like the civilized world from which they had come.