The conch serves as a transfer of power, or usurpation of power, from Ralph to Jack in chapter 8.

When Jack blows the conch, Ralph and Piggy rise obediently.  Ralph is the nominal leader, but his power is infused by the conch.  When Jack takes up the conch, Ralph surrenders control.

The sound of the inexpertly blown conch interrupted them. As though he were serenading the rising sun, Jack went on blowing till the shelters were astir and the hunters crept to the platform and the littluns whimpered as now they so frequently did. (ch 8)

Ralph realizes what he is doing, and stops himself.  He sees that he was responding to the authority of the conch, and questions Jack’s authority publicly.

“If you hadn’t called it I should have. You just blew the conch.”

“Well, isn’t that calling it?”

“Oh, take it! Go on—talk!” (ch 8)

Yet almost as soon as Ralph questions Jack, he backs down. He is beginning to submit, and the others will see this as a sign of weakness, giving more and more power to Jack until the tribe disintegrates into two, with Jack in charge of the heathens.