There are many diffrent answers, it depends on what story it is, but the most popular answer is that they turn to stone forever.
They turn to stone when the are exposed in the sun
On his first attempt at burgling in "The Hobbit," Bilbo is caught by the trolls and nearly eaten before Gandalf intervenes and saves him by tricking the trolls into staying out until dawn when they turn to stone. This encounter marks the beginning of Bilbo's adventures and his growth as a character.
The Dwarves will get captured by the giant spiders who plan to eat them, Bilbo rescues them, only for them to be captured again by the Elves.
The last dwarf to be caught by the trolls in J.R.R. Tolkien's "The Hobbit" was Thorin Oakenshield, the leader of the company of dwarves. While traveling through the Misty Mountains, the dwarves were captured by trolls, but Thorin managed to escape briefly and attempted to rescue his companions. Ultimately, Gandalf intervened, tricking the trolls into arguing until dawn, which turned them to stone. This event highlights the perilous adventures the dwarves faced on their quest.
Bilbo hides in a bush while the trolls are fighting and arguing. He tries to stay out of sight as the chaos unfolds, hoping to avoid detection. His concealment allows him to observe the trolls without getting caught, which is crucial for his safety during that tense moment.
They continue on their journey towards the Lonely Mountain.
In J.R.R. Tolkien's "The Hobbit," the trolls were fooled by the cleverness of Bilbo and the dwarves, who took advantage of the trolls' foolishness and lack of intelligence. The trolls were tricked into arguing among themselves about how to cook the dwarves, ultimately delaying their decision until dawn. As the first light of day broke, the trolls were turned to stone, a fate that befell them due to their exposure to sunlight, which revealed their true nature. This clever ruse showcases the theme of wit triumphing over brute strength.
They turn into little trolls that make your life miserable.
Bilbo and the dwarves are caught first by trolls, then by goblins. they are trapped up in a tree because of goblins and Wargs
All three trolls are turned to stone by the first light of the sun.
After they caught Bilbo, the dwarves came looking for him. As they got around the fire the trolls popped a sack over their heads. It all started when they caught Bilbo. As they were questioning him, Balin came in, quite unsuspecting of anything. The trolls jumped him before he knew what's what. Then they hid behind the trees out of the light and waited for the other dwarves, who they promptly caught in a sack.
they are amber trolls