The tunica of molluscs has a special gland cell, and its secretion can form calcification and protect the soft parts of the body, which is called the shell. The number, shape and structure of shells vary greatly, and some types are 1 spiral shells (such as snails, snails and abalone); Some species have two petal-shaped shells (such as mussels and cockroaches); Some species have eight plate-like shells arranged in tiles (such as stone turtles); Some kinds of 1 shells are wrapped in the body (such as squid, squid); Some kinds of shells even completely degenerate (such as ship maggots). The main components of shells are 95% calcium carbonate and a small amount of shellfish. Generally can be divided into three layers. The outermost layer is dark brown cuticle (shell skin), which is thin and transparent and has the function of preventing carbonic acid erosion, and is composed of chitin secreted by the edge of the mantle; The middle layer is prismatic layer (crust), which is thick and consists of prismatic calcite secreted by the mantle edge. The outer layer and the middle layer can enlarge the area of the shell without increasing the thickness. The inner layer is the nacre (bottom layer), which is composed of phyllodes secreted by the whole surface of the mantle. It has a beautiful luster and can be thickened with the growth of the body. The main chemical composition of calcite and aragonite is CaCO3. There are many concentric and annular growth lines on the outer layer of the shell, and the light and dark colors alternate, but they do not represent age; It is formed because the edge of the mantle can't continue to secrete for some reasons (lack of food, different seasons, reproductive period, etc.). ). Shellfish such as clams. Some of them have pearl-like iridescent luster, so they are used in jewelry industry to make necklaces and clothing accessories (buttons, etc. ), even installed on jewelry, more used to make shell carvings, collages, inlaid handles, etc. Among all kinds of shells, Pinctada martensii in the Torres Strait in northern Australia, Pinctada Manila in the Philippines, Pinctada burma in Myanmar, Giant mussel and Queen mussel in the West Indies are the best. A century ago, the deep-sea pearl oyster was a symbol of luxury and splendor of European aristocrats. It has a charming luster and changing colors like pearls, but it also has colorful colors different from pearls. The colorful pearl shell that breeds pearls has never been ignored and buried for thousands of years. In the late Qing dynasty, mussels and other shellfish were polished into buttons and decorated on high-end clothes in Hangjiahu area. They have always been the best friends cherished by designers. Especially in the past two years, jewelry-grade shellfish ornaments have been more and more loved by people who like handsome and natural in our city. Mother-of-pearl is a natural material, so the color and texture of each piece are very unique, which meets the demand of more and more consumers for personalized jewelry. The processing of mother-of-pearl jewelry is very complicated, and the original mother-of-pearl should be polished, cut and inlaid in detail according to the design requirements. After many processes, it can be made into pleasing shell ornaments. Shells can be divided into five classes: Gastropoda (including Oncomelania hupensis), Cephalopoda (parrot octopus), Polypoda (ivory color) and Bivalves (two shells). A small shell can also play a big role. Fan-shaped, spiral, large and small, with a little processing, or wearing, or hanging, you can escape the fate of being thrown away and show off on the wall and desktop. The large fan-shaped shells are completely decorated on the inner wall of the wooden bowl through a special process, which is more environmentally friendly to use. And if you put on a beautiful pearl, make a curtain and decorate it in front of the window, the home scene with Southeast Asian flavor will be presented immediately. If you put it by the sea, you will use it to listen to the sound of the sea, but it is very useful in a natural style home. Curtain buckles and small rings, shells can make your home show the scenery of Southeast Asia without decoration. The small conch picked up by the sea is smooth, round and shiny, and the two are matched together to make the ring of curtain buckle, which is beautiful and extraordinary. When they are attached to the curtains at home, the curtains will also be contaminated with the flavor of Shanghai style. Make a set of tableware with shells. Forks and spoons, each with its own purpose, are very interesting to put on the dining table. In ancient times, shells also served as money. Pearl is an ancient organic gem, which is produced in mollusks such as Pinctada and Pinctada. The calcium carbonate-containing mineral (aragonite) beads produced by endocrine function consist of a large number of tiny aragonite crystals. According to the research of geology and archaeology, there were pearls on the earth 200 million years ago. The international gem circle also lists pearls as lucky stones for June birthday and commemorative stones for 13 and 30th wedding anniversary. Pearls with magnificent colors and elegant temperament symbolize health, purity, wealth and happiness, and have been loved by people since ancient times. A typhoon in 2006 was named "Pearl". "The Warring States Policy Qin Ce V": "The palace of the monarch hides pearls and precious stones." Tang Lixian used the poem "Fu Gui Qu": "The pearl wins the poverty of the Dragon Palace and scratches the back of the people." Song Ming Ying Xing's "Heavenly Creations and Jade Beads": "Every pearl must give birth to a clam belly ... after the longest years, it is a treasure." Pearl's English name is Pearl, which evolved from Latin Pernulo. Its other name, Margaret, comes from ancient Persian Sanskrit, which means "son of the sea". As early as ancient times, when primitive humans were foraging by the sea, they found white pearls with colorful auras and were attracted by their crystal splendor. Since then, pearls have become people's favorite ornaments and have been passed down to this day. Shell types: tiger-spotted shell, white jade shell, luminous shell, five-claw shell, pig mother shell, pearl shell, chaste shell, tangguan shell, heptapod shell, horseshoe shell, bighorn shell, precious shell, phoenix shell, conch, cap shell, conch, tangguan shell, jade snail, octopus and quail snail. Chrysanthemum clam, sunshine cherry clam, Pacific fox clam, angel wing seagull clam, Xiufeng clam, oil painting sea fan clam, solid color sea chrysanthemum clam, safflower snail, yellow snail, lamarckian snail, West African cherry clam, snow mountain snail, eye spot snail, white star snail, map snail, hundred-eyed snail, black star snail, golden snail, fox snail and mouse snail. Bulb-shaped Eriocheir sinensis, golden brown bullet snail, golden fist snail, lip-moistening snail, crystal snail, small loquat snail, swollen loquat snail, cock snail, Darkmouth snail, golden axe snail, Gu Mi snail, reticulate long nose snail, big red snail, snipe snail, long fist snail, long fragrant snail, biting snail, etc. Martin's long-nosed snail, Hei Chi snail, twisted snail, Dongfeng snail, left-handed snail, snail, Zan's ginkgo snail, thick-tumor snail, vase snail, flame Tang Guan snail, Taiwan Province jujube snail, cone snail, thin Tang Guan snail, sea rabbit snail, purple sleeve snail, Bao Ling snail, big round snail, purple snail and so on. The formation of shells: small shells born of various large shells in the ocean (this is the origin of shells that look different), and their shells will grow bigger as they grow. So as long as you see a small shell, it may be a dead small conch.

Shell is a poem written by Manjiestam, an important representative of Akhme School in Russia, and is regarded as one of the greatest Russian poets in the 20th century.

Maybe you don't need me,

One night, from the abyss of the universe,

A shell without pearls,

I was thrown to your shore.

You rub foam carelessly, use spray,

You only care about yourself and sing stubbornly.

But you will love and you will judge.

This useless shell tells you lies.

You will catch it and lie on your back on the beach.

You're still wrapped in your old skirt,

You'll be connected to it, and it's hard to tell it apart.

The loud bells of water waves.

So, a shell with a brittle outer wall,

It's like an empty cabin,

Full of you, with mumbling bubbles,

With the breeze, with the drizzle, with the sea fog ...