- Kingdom: Animalia
- Phylum: Annelida
- Class: Polychaeta
- Subclass: Sedentaria
- Order: Sabellida
- Family: Serpulidae
- Scientific name: Serpula vermicularis
- Norwegian: rød kalkrørsmark
The red or pink tube color is characteristic for this species. There are five longitudinal and numerous transverse ridges on the tube. The diameter rarely exceeds 5 mm. The worm may grow to a length of 7 cm. The body has 200 segments. The crown consists of as many as 70 tentacles with red or white cross-bands.
It thrives on rocks, shells and other hard surfaces, in the sublittoral zone or below.
This tubeworm can be found world-wide.