A seed doesn’t need wings to travel, just something willing to eat it. Most people picture a bird doing that job, swallowing a berry and flying off before the seed drops somewhere new.

Slugs and beetles do the same thing at ground level, and a new review makes the case that nobody’s been giving them credit for it. Si-Chong Chen, a professor at the University of Hong Kong’s School of Biological Sciences, led the team behind it. She worked with researchers from the Chinese Academy of Sciences, Durham University in the United Kingdom, and Kobe University in Japan.

None of the animals in this review are the ones you’d expect: slugs, earthworms, beetles, crickets, and crabs, all eating seeds along with the fruit or plant matter around them. The seeds don’t die in the process. They pass through the gut and come out able to sprout. Kenji Suetsugu, a professor at Kobe University and a co-author on the review, pointed to one example. “A single crab can ingest over a thousand tiny seeds in a single night and later deposit them inside underground burrows,” he said.

“These humid burrows can protect the seeds from being eaten by rodents or drying out, giving them a better chance to grow.” Bird and mammal seed dispersal has received decades of attention for good reason. A monkey or a toucan can carry a seed a long way from the tree it fell off. That distance cuts down competition between a seedling and its parent, and it can push a species into new territory.

Chen’s team looked for the version that happens underground, a pathway scientists call invertebrate endozoochory. In practice, that means a seed passes through a small animal’s gut and comes out alive. Across the 43 studies the team reviewed, they found this process in at least 51 invertebrate species and 186 different plants, with records from Oceania, Asia, Europe, and North America. “If you walk through a forest, you might think only birds or monkeys are spreading seeds,” Suetsugu said. “But beneath our feet, a hidden group of gardeners is also at work.”

Chen’s team noticed something else, too. Plants that depend on ground-dwelling invertebrates tend to grow small, tough seeds tucked inside dull, plain fruit that sits close to the soil. Bright fruit up in a tree canopy is a billboard for birds. Dull fruit down in the leaf litter is easy to miss unless you’re a slug or a beetle crawling right past it.