Classification

Kingdom: Animalia
Subkingdom: Metazoa
Superphylum: Lophotrochozoa
Phylum: Mollusca

Mollusca itself has 9 classifications, with 7 extant representativies and 2 extinct classes.
Mollusks are classified by number of shells or foot shape.

The current 7 extant classes include the following.

GASTROPODS
This class has more than 60 000 unknown species, making it the largest. Gastropods include snails.

BIVALVES
This class of mollusks are the ones with two shells halves attached on a corneous hinge. This class is also known as
Pelecypods.

POLYPLACOPHORA
Organisms in this class have a shell that made with eight plates held together by a girdle.

CEPHALOPODS
There are currently over 800 know extant species in this class. They are sometimes known as ink fish to fishermen.

ALPLACOPHORA
They live in the extreme depths of the ocean and have a worm-like structure.

MONOPLACOPHORA
This class was thought to be extinct until scientists studied the fossil records in the 1960s and discovered it was a primitive
form of mollusks.

SCAPHOPODA
Scaphopoda is a class of shelled marine mollusks. They are also known as tusk shell because it resembles the shape of an 
elephant's tusk.