I was asleep when the twisty things were fighting and when they went away I was awake, and I saw something big and horrid moving in the trees" (85).
The little boy Phil tells his nightmare to Ralph in the assembly meeting as the boys discuss their fear of the beast. After the little boy has told his story, Ralph demands if anyone from the rest of the group had been wandering around.
"There was a long pause while the assembly grinned at the thought of anyone going out in the darkness. Then Simon stood up and Ralph looked at him in astonishment" (85).
Simon claims that the little boy actually saw him going or returning from his special place in the jungle, the one that he visits when he wants to be alone in chapter three. Simon has a special affinity for nature and for the island; traveling alone in the dark does not paralyze him with fear the way it does the other boys. After Simon reveals that he was actually the 'monster' that the little boy Phil saw in the dark, the other boys deride Simon's comment, and Jack claims "he was taken short" just to embarrass the boy even more.
In Chapter Five of Lord of the Flies, Ralph blows the conch, calling the boys to a meeting. During this meeting two of the small boys claim that they have seen some kind of beast. One says it comes from the forest; the other claims a beast comes out of the sea.
Ralph calls a meeting in order to set several matters "straight." One of these is "deciding on the fear." He wants to clarify the boys' fears so that they can start again and be careful about the fire. Jack stands and blames the littluns for starting the "fear talk." He scolds them and tells them that they must simply endure being frightened because fear alone cannot hurt them any more than a dream can. Further, he asserts that there is no beast in the forest.
Then Piggy speaks. He tells the littluns that fear amounts to nothing unless they become frightened of people. Soon, Phil stands up and states that he has had a horrid dream about having a struggle with "twisty things in the trees." The other littluns laugh in "horrified sympathy." Ralph tries to tell him that he has had a nightmare, but Phil denies this: "I saw something big and horrid moving in the trees."
Ralph wonders how anyone could be wandering around in the darkness. But Simon stands and takes the conch, saying that he wanted to go a place with which he is familiar. He is what Phil has seen. Ralph scolds Simon, ordering him not to go out at night. But Piggy tells Ralph that there is another boy who has seen something, a boy named Percival Wemys Madison. When he is called upon, Percival begins to cry uncontrollably. Finally, he mutters something to Jack, then he falls asleep. Clearing his throat, Jack informs the group, "He says the beast comes out of the sea."
Hearing Percival cry, the other littluns are reminded of their own fears, and they begin crying in sympathy for one another.
I believe it is the vines from the jungle.