Imagine you’re living off the coast of California, and you want to get to sunny Florida. That sounds easy enough, but there are three big problems in this imaginary scenario. First, you are a snail, so crossing even a small distance takes a lot of time. Second, there is a continent in the way. Third, you are a sea snail so you are not adapted to crawling on land.

These problems seem insurmountable and yet snails have made the journey. Osamu Miura from the Smithsonian Tropical Research Institute has found that horn snails crossed from the Pacific to the Atlantic Ocean around 750,000 years ago, while other individuals made the opposite journey around 72,000 years ago. And they probably flew