Teredo navalis, commonly called the naval shipworm or turu, is a species of saltwater clam, a marine bivalve mollusc in the family Teredinidae. This species is the type species of the genus Teredo. Like other species in this family, this bivalve is called a shipworm because it resembles a worm in general appearance while at the anterior end it has a small shell with two valves, and it is adept at boring through wood.

This species may have originated in the northeast Atlantic Ocean, but has spread around the world. It tunnels into underwater piers and pilings and is a major cause of damage and destruction to submarine timber structures and the hulls of wooden boats.