- Kingdom: Animalia
- Phylum: Annelida
- Class: Polychaeta
- Subclass: Sedentaria
- Order: Sabellida
- Family: Serpulidae
- Scientific name: Hydroides norvegicus
- Norwegian: hvitrørmark
The body length rarely exceeds 3 cm, but may include as many as 100 segments. The tube is white or brown, usually white at near the opening. The tube diameter is approximately 3 mm. The tentacles have white and red bands.
It prefers hard substrate, well below the tidal zone.
It is widespread in the North-East Atlantic Ocean, the Mediterranean and the Black Sea.