The Giant Crystal Cave at Naica Mine in Chihuahua, Mexico is one of the weirdest places on the Earth. Deep down in the bowels of the Earth, these huge shiny mineral pillars are enough to make you feel claustrophobic. This mammoth structure has been growing underneath Mexico for more than 500,000 years. It makes for an exceptional case study on how organisms survive in extreme heat and humidity. The Giant Crystal Cave was discovered by miners in 2000 and has been featured in a National Geographic documentary.