Ancient Vines is a plant block from the Ancient Cavern.
Ancient vines cannot be obtained in survival mode. Ancient vines placed outside of the Ancient Cavern can be sheared, allowing them to drop themselves. A tool enchanted with Silk Touch does not work. If broken without shearing, then ancient vines do not drop anything. However, since ancient vines only generate in the Ancient Cavern, they cannot be obtained in survival mode as attempting to break them does not drop anything, even when shearing them.
Ancient Vines generate on the ceiling in the main room of the Ancient Cavern. These are the only ancient vines that generate in the entire game.
Ancient vines can be placed on the bottom of certain blocks, or on the bottom of another ancient vine. They cannot be placed on the sides or top of blocks.
If the block above an ancient vines is broken, all ancient vines and ancient vines cap that are below the block will break. If an ancient vines in the middle of multiple ancient vines is broken, then all of the ancient vines and the ancient vine cap will break, including both vines that are above and below the broken vine.
Ancient vines can be broken by water and lava flowing into them.