Apart from the Ship worm (Teredo), a few other bivalves have highly modified shells that look nothing like a typical bivalve.

The ‘watering pot’ shell of Brechites sp.

Some of the most peculiar belong to the Family Clavagellidae. Members of this family are often called ‘Watering-pots’ because their shells are reduced to a small remnant on the sides of a long thin tube that can reach 10 cm or more. Some of these species burrow into soft sediment, others attach themselves to small rocks.

The animal feeds through siphons extending to the open end of the shell, which protrudes slightly above the bottom surface. The animal’s front end is placed downward in free-living species, and is capped with a peculiar perforated disc that looks exactly like the expanded head of a gardener’s watering-pot, hence their common name. Water movements through the disc may help the animal embed itself further into the sea-bed and could serve as a means of pulling food particles into the body area.