Note: The barnacles in the key below belong to the superorder
Thoracica (acorn and goose barnacles), to which the large majority of local
barnacle species belong.  For parasitic barnacles (Order Rhizocephala,
Family Sacculinidae) parasitic on the black-clawed crab Lophopanopeus
bellus click here. 

1a

Parasitic, not recognizable as a barnacle as an adult but has
a cypris larva