A galvanic anode, or sacrificial anode, is the main component of a galvanic cathodic protection system used to protect buried or submerged metal structures from corrosion. Wikipedia

Main component of cathodic protection Wikidata

An anode used to protect buried or submerged metal structures from corrosion, made from a metal alloy with a more "active" voltage (more negative electrochemical potential) than the metal of the protected structure, so that the anode material corrodes and is consumed in preference to the structure. Wiktionary