Partula snails are a family of fingernail-sized mollusks native to French Polynesia. For a long time, these critters were both scientifically and culturally significant to researchers and the native (human) population—the reason their near extinction in the late 20th century set off a global, systematic project to bring them back.

So far, 2025 has been a great year for Partula snails. In spring, a subspecies of the family was reclassified from Extinct-in-the-Wild to Critically Endangered on the IUCN Red List of Threatened Species. Now, the global collaboration announced that it had reintroduced over 7,000 Partula snails back into their island homes this year alone. It’s the largest release of the group since 1991, when the breeding program began, according to a press release from the Zoological Society of London (ZSL) on November 13.

The snails’ comeback also speaks to the value of carefully planned, long-term conservation projects. That said, it never hurts to be too vigilant when it comes to conservation—the reason that the researchers have left a small souvenir on their shells: a small dab of white UV reflective paint—basically glow-in-the-dark paint. This will help experts track the nocturnal snails’ well-being in the dark, ZSL explained.

Why Partula snails almost went extinct

In the late 20th century, Partula snails were nearly decimated by an ironic yet predictable human mistake. Back then, a carnivorous snail species was introduced to the Polynesian islands to control another invasive species—leaving the native Partula snails caught in the crossfire.

This was disastrous from a scientific perspective, but the shells of each species were an important part of the cultural identity of the island nation, meaning that “the damage went beyond harming fragile ecosystems—it was a loss of Polynesian heritage, too,” ZSL noted in an introductory page for the conservation project.

At the time, the situation appeared rather bleak; scientists were only able to save just nine individuals of one subspecies in 1991.

A glorious comeback

But that has clearly changed for the better, as the collaboration has managed to release over 17,000 snails back into the wild in the last 30 years. Some of these snails had to travel over 9,000 miles (15,000 kilometers) back home. But initial assessments have suggested that the snails have taken the transition well.

For instance, during the release, the team noticed a baby Partula snail without the UV paint—that is, the snails were already breeding in their native environment. What’s more, the team also took this opportunity to check up on the reclassified Partula subspecies, which, to their pleasant surprise, appeared to be thriving in and outside of their original release range.

“These mollusks play an important role in the health of their forest ecosystems, eating decaying plants and fungi, reducing the spread of disease and cycling important nutrients through the food chain,” explained Justin Gerlach, a researcher at Cambridge University in the United Kingdom, in the statement. “By restoring wild populations, we can improve the state of the forests.”

“Wildlife globally faces unprecedented challenges, and every single species is a precious part of the interconnected web of ecosystems that we all rely on,” added Paul Pearce-Kelly, a ZSL researcher who leads the international Partula conservation program. “So today’s news is not only a moment of hope for these snails, but for nature and people globally.”