The cave formations in China's southwest Guangxi Zhuang region almost look like a different world.
This region of China is home to the world's largest concentration of these karst formations, the largest cluster of sinkholes, and the world's most enormous cavern. The relatively pristine condition of these caves also means it's been a trove for scientific discovery.
During their most recent expedition exploring the caves, Chinese and French cavers spotted an extremely rare fish called a Sinocyclocheilus grahami, or golden-line barbel. According to the International Union for the Conservation of Nature, the species is critically endangered.
Rare Blind Fish
The golden-line barbel was once endemic to Lake Dianchi in China's Yunnan province, but now the fish is thought to only survive in about 20 spring ponds and one lake tributary. Invasive species, overfishing, and pollution have caused the species to decline by more than 80 percent over the last three generations.
Golden-line barbels belong to a family of fish called Cyprinidae that also contains freshwater fish commonly seen in the U.S. like carps and minnows.
But unlike its cousins, the small ghostly white fish, barely measuring an inch, is also blind.
"We found blind fishes at three different areas, and there were many of them," Jean Bottazzi, a French caver who has spent several years exploring the region, said in an interview with Chinese state media. "At one area, we saw blind fishes and other fishes, which were preying on the blind fishes, so it is really safe to say that there are many blind fishes in the cave water here."
In addition to the rare fish, the cavers also claim to have found large cave halls, underground rivers, and other cave creatures.
During a 2016 expedition, cavers found a 1,300-foot sinkhole with a clear pool at the bottom. A similar and rare species of white fish and white insects were also reportedly found.
South China's Karst is a UNESCO World Heritage Site that covers more than 400,000 acres. In addition to the cave systems, the karst landscape has produced large stone towers, natural bridges, and gorges.