Might be all right served up with garlic butter. And mark this, in these days of making both ends meet - THEY ARE FREE.
Boxy - that's even worse than the things I do to them, at least they die immediately. All shut into a jamjar or bottle they will die a horrible death. Best to put them in a bucket of salted water. They should die quickly. They do not like salt.
My last garden used to be full of slugs and my poor plants were getting attacked left, right and centre.
I used copper tape all along the bottom of my containers, which did seem to work.
They never bothered with my pots, tomatoes (though these are still only leaves), apples, Rosemary, Curry plant, Courgettes or Blueberries.
However, they have gone to town on my strawberries, rhubarb and lettuce :(
I know it's not nice but I can't bear the goop if you drown them. I stood on a slug in bare feet the other day (my bare feet, not the slug's) - it was disgusting.