This is a snail you probably are familiar with, at least if you are in Europe. It was first reported in Sweden in 1975, in Hälsingborg, a naval city in the southwest of Skåne. From there it spread over the country and you find it as far north as Umeå in northern Sweden, only 395 km from the arctic circle. The snail is called Spanish forest snail or "Killer snail" because it sometimes killes and eats other snails. With no natural enemies and because it eats most green stuff it has been an enemy for all farmers and garden keepers and so far theres no way to get rid of it once it's in your area.
Today I saw it, actually for the first time by The Pond, close to where I live. I've no idea why it hasn't been common just here earlier. When I recently was in the south of Sweden I was warned to walk with bare feet outside at night because I would surely tread on one. In my garden I saw the first one I ever seen here three weeks ago. I don't know if there is any reason for it not to like it here, or maybe I haven't been observant. Though, if you see one you normally see a lot of them and so far it's not like that in my garden. Maybe they are finally closing in even here.