Balanus glandula (commonly known as the North American acorn barnacle or common acorn barnacle) is one of the most common barnacle species on the Pacific coast of North America, distributed from the U.S. state of Alaska to Bahía de San Quintín near San Quintín, Baja California.

[1] They are commonly found in the upper intertidal zone on mussels, rocks and pier pilings.

[1] The shell is formed by overlapping plates and has a calcareous basis.

The white operculum has heavily ridged walls.

[1] It has been intensely studied in recent years as a model species for linking physical oceanography and population genetics (or phylogeography) surveys.