[Update: data in the comments about how slugs and maggots are good for you. Comes from a doctor, so probably not a joke.]
I've seen one before, they are these tiny, black things, without a house, so small they can get under the garden door. [Update: seems this one is not so black and slightly bigger. Also, by "house" I meant "shell", I was thinking in Danish there, it's called a "snail's house" in Danish.]

Coming in from my early morning constitutional today, I found another of the little Fokkers, not just trails this time. Or maybe the same one, because as you can see, I did salt the entrance yesterday. ... Maybe I locked it in! (Anyway, I found a leaf outside and carried him out.)
They're really small, less than an inch and thin.











