Balanus nubilus

Balanus nubilus
Giant acorn barnacles with cirri extended for feeding
Scientific classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Thecostraca
Subclass: Cirripedia
Order: Balanomorpha
Family: Balanidae
Genus: Balanus
Species:
B. nubilus
Binomial name
Balanus nubilus
Darwin, 1854

Balanus nubilus, commonly called the giant acorn barnacle, is the world's largest barnacle, reaching a diameter of 15 cm (6 in) and a height of up to 30 cm (12 in), and containing the largest known muscle fibres.