- Kingdom: Animalia
- Phylum: Nemertea
- Class: Anopla
- Family: Lineidae
- Scientific name: Lineus longissimus
- Norwegian: kjempeslimorm
This ribbon worm deserves its name. It is the longest nemertean, and may be the longest animal we know. A body length between 5 and 10 meters is common, but there are registrations 30 meter long worms. It is believed that the giant ribbon worm may reach 60 meters when fully stretched. The color may vary from dark olive-brown to almost black. A number of lighter, usually beige, stripes run along the body.
It thrives on lower shore, on rocky or sandy bottom, where it coils up under boulders and in crevices.
It is registered along the coast of Europe, from Gibraltar to the British Isles, Norway and Iceland. It is not known from the Mediterranean.