Lepas (Anatifa) anserifera Linnaeus, 1767
This is not a Mollusc. Other non-Molluscan Phyla (Echinodermata, Brachiopoda etc) have been included to help identify species that may be mistaken for Mollusca, but actually are not.
Arthropoda (Phylum) > Crustacea (Subphylum) > Hexanauplia (Class)
> Thecostraca (Subclass)
> Lepadiformes (Order)
> Lepadidae (Family)
> Lepas (Genus)
> Anatifa (Subgenus)