In the late 1890s, Carl Chun, a biologist at Leipzig University, found something unusual: a candy bar-sized larvacean surrounded by a translucent blob of snot the size of a balance ball. But the slimy creature wasn't seen again, until now.

Chun led a project called the Valdivia Expedition. He and his team sailed the South Atlantic, drawing up all sea life they could catch. In the 32,000 nautical miles they traveled, the team found numerous creatures new to science—so many it took forty years to publish all the descriptions, which filled 24 volumes.

But the giant larvacean caught his eye, dubbing the creature Bathochordaeus charon after the boatman who ferried passengers across the river Styx. Most larvaceans are millimeter-sized tadpole-shaped tunicates with a primitive spinal cords. Every day the creatures build a new “house” out of snot-like material to catch debris, plankton and other microscopic food bits in its sticky web. After it becomes packed with ocean bits, they discard the slimy house and build a new one, reports Tia Ghose for LiveScience.

Chun's larvacean, however, was much larger than the average creatures, growing nearly four inches long with a snot house up to three feet across. He and his team created a detailed drawing of the strange creature. But his original specimens were lost and for over a century another one was not identified, leading many to believe he had made a mistake, confusing the other species of giant larvacean, B. stygius, for a new species.

Now, over a century after Chun found that creature researchers at the Monterey Bay Aquarium Research Institute (MBARI) found another example of B. charon—and they have photos to prove it. During a routine ROV sampling mission in Monterey Bay, senior research technician Rob Sherlock spotted the nine centimeter-long creature, according to a press release. He asked the ROV operator to stop and collect the creature.

After the animal came to the surface, Sherlock examined it through a microscope. Though he was initially puzzled, he soon realized it was the elusive B. charon. Specialists confirmed it is the long lost species using genetics.

“It felt like Chun had finally been vindicated after years of doubt,” Sherlock tells Ghose.

Chun actually had been vindicated a dozen times previously, but researchers hadn't yet realized it. After the discovery, the MBARI researcher Kristine Walz went through 25 years of ROV footage, looking carefully at the larvaceans, according to the release. Mixed in with the hundreds of B. stygius images were 12 of the elusive B. charon, meaning that while the creature is rare, it’s not impossible to find.

Even so, this latest discovery resolved any lingering doubts about the creature, closing the case of the slimy ocean blob.