- Kingdom: Animalia
- Phylum: Annelida
- Class: Polychaeta
- Subclass: Sedentaria
- Family: Arenicolidae
- Scientific name: Arenicola marina
- Norwegian: fjæremark
The front (anterior) region is thick, while the back (posterior) region is long and narrow. The back region consists of 19 segments of which the last 13 bear bushy gills. The blow lug may reach a total length of 20 cm. It comes in a great variety of colors, most common are pink, red, green, dark brown or black.
It can be found on lower shore, where it lives buried in sand or muddy sand with the head end closest to the surface.
It is common along most coasts of Europe, from the Mediterranean to the Arctic.