What Are Periwinkles?

Periwinkles are tiny little snails that everyone sees as ubiquitous which means they're everywhere. On the coast here in New England these are actually a non-native species that came from Europe manyMany years ago but now we see them as commonly as all the seaweed and we think nothing of it They're supposed to be here. And something like a periwinkle a little snail when you say  that could have come on the ships right it sort of sucks to the side of a ship and comes over that way.