In Chapter 1, Ralph and Piggy find a seashell in the lagoon. Piggy realizes that it is a conch. He says that it can be used like a horn. Here, we have the first example of Piggy's intellect. His physical weaknesses make him an easy target for a bully like Jack, but his intellectual abilities make him stand out as the academic of the boys.
After a few tries, Ralph gets a loud, booming sound from the conch:
A deep, harsh note boomed under the palms, spread through the intricacies of the forest and echoed back from the pink granite of the mountain. Clouds of birds rose from the treetops, and something squealed and ran in the undergrowth.
Little by little, the boys gravitate to Ralph and Piggy, some asking for the man "with the trumpet." Ralph informs them that he's summoned them to a meeting. The conch has been used successfully. It is a tool for organizing the boys on the island. It becomes of symbol of order and, with these meetings, it gives the boys a chance to assign jobs and responsibilities in a civilized way. Ralph has leadership qualities and Jack does as well. But with Ralph holding the conch when the boys arrive for the first meeting, he seems to command more authority. One of the boys shouts, "Let him be chief with the trumpet-thing."
As some of the boys become less civilized and more irresponsible, the effectiveness of using the conch to keep order diminishes.