More than 80% of our ocean is unmapped, unobserved and unexplored. That means there is wildlife, and perhaps entire ecosystems that we have yet to discover or understand. This is part of why I find the ocean so exciting—it’s full of mysteries yet to uncover.

For example, just last month a new species of ghost shark was discovered hilariously named the Stubby Chimaera.

Chimaera are fascinating creatures found at depths of more than 1,500 feet. They live in the deep, dark ocean making them hard to study and much of their behavior is unknown.

But there are some mysteries of the ocean hiding right beneath our noses. Take this story that recently caught my attention as a perfect example. That is the story of the sand octopus of South America.

170 years ago, Americans set out on the United States South Seas Exploring Expedition. It’s important to remember that at this time America was a relatively new country with a small Navy. An expedition like this was daring and risky. Luckily, it paid off and the naturalists onboard brought back an overwhelming number of specimens for the small but growing scientific community at home. Among this plethora of treasures was a humble sand octopus that would help identify his entire species as Callistoctopus furvus.

That was nearly where the story of the sand octopus ended. After more than a century had passed without a clear sighting, scientists began to doubt it had ever existed and believed the specimen had been misidentified.

But while the sand octopus had evaded the scientific community, it had not evaded local fishermen in Brazil. They occasionally caught sight of the rare octopus in shallow waters. They sometimes called it an “eastern octopus” because they would often spot it when there was a persistent wind coming from the east, or a “sand octopus” because of its propensity to bury itself in the sand.

That burrowing technique was one of the observations that interested a scientist named Manuella Dultra who helped rediscover Callistoctopus furvus. She had been working with local fishermen to study octopuses and encouraged them to capture videos and pictures of the rare sight. No other species of Callistoctopus had ever been seen burrowing before, meaning it was possibly a new species.

For years, Dultra talked with fishermen to gather local knowledge on the behavior of this sand octopus. She and her colleagues conducted interviews with local fishermen, tagged along for their fishing trips and learned traditional fishing techniques to get specimens. They combined this work with scientific techniques of identification like genetic sequencing to find that this octopus was the same one found more than a century ago. The mysterious case of the Callistoctopus furvus could finally be closed.

What I love most about this story of the lost and found octopus is that it reminds us not only of how much of the ocean there is yet to explore but how much knowledge of ocean mysteries lies with the people of coastal communities that live and work there every day. Octopuses aren’t hiding in the deep waiting to exclusively show themselves to official expeditions. They can be glimpsed by fishermen out on the job whose knowledge can help us unravel the mysteries of the seas they rely on. It was the partnership between scientists and local experts that helped crack the case of Callistoctopus furvus and helped rediscover this lost octopus.