It’s hard to miss Mount Lico, a relatively isolated cliff jutting out 700 meters (nearly 2,300 feet) above the plains of northern Mozambique. Yet for hundreds of years, people were unaware that inside the ancient volcano lay a hidden rainforest, protected by the volcano’s high walls.

Discovered by conservation biologist Julian Bayliss in 2012, the untouched biosphere is a gift for scientists. The only disturbances it has experienced over centuries are natural, such as droughts, as opposed to man-made. And so it offers a benchmark that scientists can use to compare the full effect of human interference on rainforests.

Now, for the first time, scientists have scaled the 125-meters up a near-vertical rock face to explore the undisturbed rainforest within. Bayliss took five years to assemble a team that included biologists, botanists, lepidopterists, and other experts from Mozambique, Swaziland, South Africa and the United Kingdom. The team also included rock climbers who trained the scientists for the expedition from May 10-24—an adventure that sounds straight out of a Jules Verne novel.

After only one expedition, scientists have already found a new species of butterfly and a mouse species that has yet to be classified, and expect to find more previously undiscovered animals. Because Mount Lico’s habitat is a rainforest, unique plants and animals have developed there, and can help us better understand both the past and future of the natural world.

Mount Mabu from above

The discovery is also noteworthy because it’s the second undisturbed rainforest that scientists have found in Mozambique thanks to Google Earth—offering an example of how big data can lead to new discoveries in long-overlooked habitats. In 2005, Bayliss noticed Mount Mabu, a 1,700 meters (more than 5,500 feet) mountain range that appears in the middle of a savannah. Bayliss spotted Mount Mabu while searching the earth’s surface for undisturbed rainforests. The mountain range looked similar to one he was already studying in neighboring Malawi, but scientists had never documented it.

Bayliss and his team found a high-altitude rainforest on Mount Mabu. Expeditions there have revealed species like the so-called “ghost slug,” a reptile that is halfway between a blind snake and a lizard, and new and unidentified species of fungi and other plants. Mount Lico, a more isolated ecosystem, may reveal even more unique flora and fauna.

Of course, the locals had always known about Mount Mabu—but scientists had never explored it. The discovery was also remarkable in the wake of Mozambique’s civil war from 1977 to 1992, which ravaged the much of the country’s natural environment as it reigned terror in its citizens. Ironically, both Mount Mabu and Mount Lico were partly protected by the war, which slowed industrialization and migration to Mozambique’s north.

Now, it’s up to the Mozambican government to protect these lost rainforests. “All of these northern Mozambican mountains need protecting,” Bayliss told Quartz. “Maybe this can be a call to the government to take some action.”