Barnacles are often found on boats or other objects and landscape in contact with the ocean.
These arthropods encrust themselves to hard surfaces, growing their shells onto the surface and permanently anchoring them to their living place.
Barnacles cannot be interacted with, and function as a world object rather than a creature. Certain barnacles, however, will open and emit a strong dose of radiation when the player makes contact with them.
Barnacles appear in Fallout 4.