There are numerous theories abound about the world's end, from the Mayan calendar to future predictions. Yet, a lesser-known belief centers on a Shivling in Uttarakhand's Patal Bhuvaneshwar cave. Legends claim it grows annually and will signal apocalypse upon reaching the cave ceiling. The cave, steeped in Hindu lore, houses four gates and ice-like pillars, each symbolising an era.