Visitors to southern Spain can now step inside an otherworldly rock formation. A giant geode recently opened to the public near the town of Pulpí. It’s one of the largest crystal-filled rocks ever discovered.
The geode began forming millions of years ago as mineral-rich water seeped underground. The water slowly evaporated, changing from a liquid to a gas, leaving behind crystalized minerals. Over time, the crystals gradually grew. Some now are 2 meters (7 feet) long.
To enter the geode, people squeeze through a small opening at one end. “The first time I stepped inside, my heart raced because I was seeing something incredible,” says Javier García Guinea, a geologist at the National Museum of Natural Sciences in Madrid, Spain.