I walk to to work from the train station. On the way into our building, on some mornings I notice that our walkway is sprinkled with snails. My guess is that the snails can't stand it when the sprinklers are turned on, so they retreat to the sidewalk. Snails were quite rare in Ohio, but perhaps the lack of cold winters allows them to thrive here?
Banana slugs are endemic to the native forests (i.e. redwoods). They're rather impressive, especially the first time one sees one of them. Typically they're about six inches long and brownish yellow. They're slimy, true, but the slime doesn't stick to your hand. They've very cool beasts, I think.