On printed circuit boards, a change such as soldering a wire in order to connect two points, or addition such as an added resistor or capacitor, subassembly or daughterboard
marine crustaceans with feathery food-catching appendages; free-swimming as larvae; as adults form a hard shell and live attached to submerged surfaces
Barnacles are small shellfish that fix themselves tightly to rocks and the bottoms of boats. a small sea animal with a hard shell that sticks firmly to rocks and the bottom of boats (barnacle type of goose (12-21 centuries), from bernaca; from the former belief that the goose was born from a barnacle). Any of a majority of the 1,000 species of the subclass Cirripedia of marine crustaceans that, as adults, are covered with a shell made of hard calcium-containing plates and are permanently cemented, head down, to rocks, pilings, ships' hulls, driftwood, or seaweed or to the bodies of larger sea creatures, from clams to whales. Barnacles trap tiny particles of food with their cirri, feathery retractable organs that emerge from openings between the shell plates. Adult barnacles commonly are hermaphrodites