- Kingdom: Animalia
- Phylum: Echinodermata
- Subphylum: Echinozoa
- Class: Holothuroidea
- Order: Dendrochirotida
- Family: Cucumariidae
- Scientific name: Ocnus lacteus
- Norwegian: -
This tiny sea cucumber usually has a body length of 1 cm, but may reach 4 cm in rare cases. The skin is white and its appearance is dominated by spines or tube feet organized in five zigzag rows. Its appearance is very similar to the slightly bigger O. planci.
It lives on stony sea floor, but can occasionally be seen crawling on the leaves of seaweed and algae. The depth range is 0 to 200 meters.
It is widespread in the Arctic region, North-East Atlantic Ocean and the Mediterranean.