If you call the assembly of the dark the second meeting (with the 'first' being when they all crowded around the conch on the beach) then the added significance of the conch in Lord of the Flies could be the added authority the conch is given - and gives. The shell takes on a mysterious authority both of it's own and given to it 'by concensus' (the boys) where no-one is supposed to speak unless they are holding the special symbol - the conch. Ralph tries to prepare himself for this, psyching himself up by ordering his ideas beforehand. Here, another symbol comes into play too - Piggy's glasses - as he wishes he had the vision and clear-headedness that Piggy has. He tries to emphasise the old rules and get them going again, but eventually people start grabbing the conch from each other and order breaks down again. The importance of the conch seems to diminsh.
In Golding’s book "Lord of the Flies,” the conch is used to call the boys to assemble. The island has been surveyed and Ralph wants to share with his group that the island has the things that they will need to survive. At the second meeting the conch becomes the symbol of the right to speak and a call to order. When Ralph tries to get the children to focus he blows the conch. When he tries to make them laugh and not be as afraid, he waves the conch drawing laughter. It is in the assembly that the determination of making rules arises.
The primary use of the conch is to be passed around and whoever holds the conch may speak. This prevents each child from speaking at once and creates a sense of order.
"I'll give the conch to the next person to speak. He can hold it when he is speaking."(33)