As their name suggests, little brown barnacles are little (up to 6 mm across, versus 22 mm across for Balanus glandula) and brown (or rather, grayish brown).
If you find a barnacle that is small and gray, but still may be a small specimen of a different species, look at the sutures between the rostrum (the widest end plate of the "volcano") and the adjoining plates: the rostrum underlaps the adjoining plates, whereas in local species of Balanus, the opposite is true.
- WoRMS Page for Chthamalus dalli
- Search Arctos Database for Chthamalus dalli (Southeast only)
- Search Arctos Database for Chthamalus dalli (entire database)
- Encyclopedia of Life search for Chthamalus dalli
- iNaturalist Observations for Chthamalus dalli in Southeast Alaska