Details of the creature, which can reach up to 1.55m (5ft) in length and 6cm (2.3in) in diameter, were published in a US science journal.
The giant shipworm spends its life encased in a hard shell, submerged head-down in mud, which it feeds on.
Though its existence has been known for years, no living specimen had been studied until now.
Despite its name it is actually a bivalve, which is the same group as clams and mussels.
