In Lord of the Flies what does the conch stand for?

A conch is a marine mollusc which lives in a coiled shell which it makes itself. As the conch gets larger it increases the size of its shell. The conch in the book is an empty shell, about the size of a large coconut. There is a small hole worn into the shell and when Ralph blows into this small hole the air travels through the shell to emerge at the large open end and produce a loud booming note.