And the aggressor is this little slug called the Spanish slug (or in Norwegian - brunsnegl). According to Wikipedia:
I found the specimen depicted here yesterday in a garden in the neighbourhood. During the later years it has been a popular pastime among the garden owners in Norway to chase these slugs, as they apparently eat many varieties of flowers and bushes. There also seem to be a contest among the gardeners about who can kill the most. "Today I took 345" you can hear from one. "That is nothing - I caught 467" says his neighbour satisfied. It reminds me of both P.G. Wodehouse and Monty Python; at the same time.
The Spanish slug, more commonly known in English-speaking countries under its Latin name, Arion lusitanicus, is a species of air-breathing land slug, a terrestrial pulmonate gastropod mollusk in the family Arionidae, the roundback slugs.
This is a highly invasive slug species. It is often considered a pest, not only in areas where it has been accidentally introduced, but even in places where it is indigenous.
I am safe - they don't eat moss.