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The conch shell becomes the symbol of authority for the boys in the early days on the island. It is an easy way to attract attention if the boys are scattered in different areas of the island.
We can use this to call the others. Have a meeting. They’ll come when they hear us—...They obeyed the summons of the conch, partly because Ralph blew it, and he was big enough to be a link with the adult world of authority….
The conch shell is a tangible item that can be passed from speaker to speaker, enforcing the rules that only one person is to talk at a time and the others are to listen.
'Whoever holds the conch gets to speak'...Ralph waved the conch. 'Shut up! Wait! Listen!' He went on in the silence, borne on in his triumph.
The shell is breakable but beautiful, thereby demanding that it be handled carefully and respectfully. When the conch shattered, the final connection to civilization and order and authority beyond mob rule was also broken.
The conch shell, because Ralph first used it to call all the boys to the beach for an assembly. It gives him authority and is a symbol for it too.