barnacle (n.) Look up barnacle at
early 14c., bernak; earlier in Anglo-Latin, bernekke, early 13c., "species of northern European wild goose;" as a type of "shellfish" found in clusters on submerged wood, first recorded 1580s. Of unknown origin despite intense speculation.

The earliest form looks like "bare neck," and one of the Middle English synonyms was balled cote, but this might be folk etymology. Often said to be from a Celtic source (compare Breton bernik, a kind of shellfish), but the application to the goose predates that of the shellfish, and the word seems to have arisen in English. The goose nests in the Arctic in summer and returns to Europe in the winter, hence the mystery surrounding its reproduction. It was believed in ancient superstition (and as recently as late 17c.) to hatch or develop from the barnacle's shell, possibly because the crustacean's feathery stalks resemble goose down. The scientific name of the crustacean, Cirripedes, is from Greek cirri "curls of hair" + pedes "feet." Meaning "person holding tenaciously to an office or position, useless or incompetent jobholder" is from c. 1600.