shellfish
[For the right pronunciation of this word, please click here.]
Some species of ‘shellfish’ have two shells – bivalves or double shelled, some have only one shell – univalves or single-shelled.
The “shellfish” family falls under three main group: molluscs; crustaceans; and ‘echinoidea’ or “echinoderm” .
Molluscs:

molluscs
this group is divided into three main parts: bivalves or two shells; univalveor single shell; and animals without shell (cephalopods). The examples of bivalves or two-shelled animals are: clam, oyster, mussel, sandshell, shipworm, cockle, paddock.
The examples of univalves or single-shelled animals are: limpet, cowrie, tower shell, tusk shell, whelk, winkle, conch, snail.
The examples of ‘cephalopods’ or animals without shell are: squid, octopus, cuttlefish.
Crustaceans:

crustaceans
the animals in this group are without bones or shells, but with a hard outer cover, a soft shell, called ‘cuticle or cuticula’.
The examples of ‘crustaceans’ are: crab, crayfish, crawfish, lobster, shrimp, prawn.
Echinoidea:

echinoidea
the animals in this group are mostly ball-shaped body with spines; the body is covered with a hard substance ‘shell’ which is called a ‘test’ which is inside a layer of skin.
The examples of ‘echinoidea’ are: sea urchins, sea cucumber, sand dollar, sea star or starfish.

oyster pearls
The shellfish are an important major sea food!
The ‘shellfish’ are the most numerous of the sea animals, and have been hunted (harvested) for thousands of years! The meat of the shellfish is eaten and the shells are used for different purposes!
The shells of the shellfish have been used as ornaments, decorative items for hundreds of years. Some kinds of shells were used as money in olden days.

cowrie
The conches have been used as ornaments and decorative items. Conches are used as ‘horns’, to announce the beginning of a battle, or a religious rite in some religions by blowing them, especially in Buddhism and Hinduism!
Oysters have been harvested for hundreds of years for “pearls” they produce! Some pearls are very beautiful to look at, and the natural pearls are very expensive! Pearls come in many colours. These days pearls are cultured (grown) artificially on farms!
The shell of ‘cowrie’, one of the single-shelled animals, was used as money some thousands of years ago. It has also been used as dice in some ancient board games!
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