Shipworms are not worms at all, but rather a group of unusual saltwater clams with long, soft, naked bodies; they are marine bivalve molluscs in the family Teredinidae
. They are notorious for boring into (and commonly eventually destroying) wood that is immersed in sea water, including such structures as wooden piers, docks and ships; they drill passages by means of a pair of very small shells borne at one end, with which they rasp their way through. Sometimes called "termites of the sea", they also are known by the common name "Teredo
worms" or simply "teredo".