any of a number of barnacles (genera Lepas and Mitella) that attach themselves by a long, fleshy stalk to rocks, ship bottoms, etc.
Origin:
from the fable that geese grew from them
See goose barnacle in American Heritage Dictionary 4
noun
Any of various barnacles of the genus Lapas, having a fleshy stalk that attaches to rocks or floating objects such as ship hulls. Also called gooseneck barnacle.