There are many which might have oval or close to oval shells, but one that comes to mind quickly is the cowry, some of which are nearly perfectly olive shaped (Class Gastropoda, Family Cypraeidae).
Such mollusks are bivalves (two shelled that are hinged): cockles, oysters, mussels, scallops, etc.
Chitons Have 8 piece shells.
8-tentacled mollusk
Octopus
they live in the shells.
most have shells
They have shells.
Mollusks are defined as Bivalves. They are called Bivalves because they have two shells. Cnidarians such as Jelly Fish do not have shells which define a bivalve (mollusks).
Mollusks have soft body and hard shells but some don't even have shells.
clown fish
Slugs,Octopus
crustations
Yes, they are mollusks as well
Mollusks are soft bodied animals that can have no shells,1 shell or even 2 shells. Snails, clams, sea slugs, clams, scallops, oysters, octopuses, and squid, are some types of Mollusks.
Norman W. Lermond has written: 'Shells of Maine' -- subject(s): Mollusks 'Shells of Maine' -- subject(s): Mollusks
mollusks are slow-moving in the way that they are soft-bodied animals and protected by shells.