The White-tuft Protula, Protula tubularia, is a marine worm belonging to the class of sedentary Polychaetes and the order of Serpulidae which lives in a white calcareous tube and is present throughout the Mediterranean Sea at depths that can vary from 10 meters to over 100 metres. It is a very common annelid.

Filograna implexa (Salmacina incrustans) is a marine species of tubular worm belonging to the class of sedentary Polychaeta of the Serpulidae family. This species is found in the waters of the Mediterranean Sea, the English Channel, the North Sea, the Gulf of Mexico and off the coast of Monzambique, and from South Africa to New Zealand.

Protula tubularia is a sedentary Mediterranean polychaete also present on the two sides of the Atlantic and in other seas. The vermiform body is protected by a solid calcareous tube, up to 1 cm broad, which the animal builds around, after having chosen for fixing itself a ridge where the currents rich in plankton pass. From the tube in which it moves, which is the house chosen for life, two elegant gill crowns come out ...