Olives (Family Olividae) are usually smooth and shiny shells with various colors and patterns. Their name is derived from their olive-like shape.

Monotocardia Order contains most of the sea shells found in the oceans. In this group, the right-hand side organs are not developed, and the animal lives with just the left side organs (gill and auricle) only.

Gastropods (Class Gastropoda) contain the snails, conchs, and similar snail-like animals. There are about 105,000 species of gastropods. This class is divided into several separate orders:

    Sub Class Streptoneura (57,000 species)

      Order Diotocardia:   Two sets of organs
      Order Monotocardia:  One set of organs
    
    Sub Class Euthyneura   (48,000 species)

      Order Cephalaspidea: thin shells, etcetera
      Order Nudibranchia:  sea slugs        
      Order Pulmonata:     snails and slugs

Mollusks (Phylum Mollusca) are a large and varied group of animals. Some species are found on land; others are found in freshwater; many are found in the oceans of the world. The most familiar mollusks have an external shell surrounding a soft body. Well-known examples of mollusks are snails and clams. The major classes are as follows:
  
   Ablacophora:                  Worm appearing
   Polhyplacophora (Amphineura): Chitons
   Scaphopoda:                   Tusk Shells
   Gastropoda:                   Gastropods
   Bivalvia (Pelecypoda):        Clams, etcetera
   Cephalopoda:                  Octopus, Nautilus
   Monoplacophora:               A recent discovery

Animal Kingdom contains numerous organisms that feed on other animals or plants. Included in the animal kingdom are the lower marine invertebrates such as sponges and corals, the jointed legged animals such as insects and spiders, and the backboned animals such as fish, amphibians, reptiles, birds, and mammals.