- Kingdom: Animalia
- Phylum: Echinodermata
- Subphylum: Echinozoa
- Class: Holothuroidea
- Order: Dendrochirotida
- Family: Cucumariidae
- Scientific name: Thyone fusus
- Norwegian: sjøagurk
Normally, only the thin, brown tentacles are visible, as they stretch 10-20 cm above the seabed. The buried body is tapered in both ends and may reach a length of 20 cm. The tube-feet are scattered all over the body.
It prefers sheltered locations with gravel or shell substrate. It has been registered on depths ranging from 10 to 615 meters.
It is distributed from Iceland and Norway to Madeira and the Mediterranean.