In Icelandic tradition, the Huldufólk, or “Hidden People,” are human-like beings who live inside lava rocks, hillsides, and boulders, emerging only when they choose. They are described as beautiful, quiet, and fiercely protective of their homes; road crews and builders in Iceland still alter construction plans to avoid disturbing supposed elf stones, a practice documented into the 21st century. Encounters often involve mysterious knocking from inside rocks, sudden disappearances, or travellers being helped or warned by a polite, unseen voice.