17 17 French natural scientist René Amor published the results of his years of research: foreign bodies enter animals or animals themselves produce parasites and other diseases. In order to protect themselves, animals secrete calcium carbonate-based substances to surround foreign bodies or injuries and form stone-like objects. This process is the formation and growth of pearls; However, not all these stone bumps mainly composed of calcium carbonate belong to "pearls" in the sense of jewelry and jade science. In view of people's habit of calling it "pearl". We can only think that pearls in a broad sense can be regarded as blocks with calcium carbonate as the main component secreted by animals to protect themselves.

Many animals have this function. Li Shizhen's Compendium of Materia Medica lists dragon beads, snake beads, fish beads, shark beads and turtle beads. , and explained the location of the "bead": the dragon ball in the jaw, the snake bead in the mouth and so on. Newspapers also report from time to time that some people "have pearls" and others "have pearls in their eyes". 1in may, 1987, 18-year-old Japanese young woman Michiko was hospitalized with abdominal pain and lower body bleeding. Married for a year, confident pregnant for seven months. The doctor couldn't hear the fetal sound during the examination, so he had a laparotomy. The doctor was surprised to find that a "pearl" weighing 1.36kg was delivered, and someone offered $200,000 to buy this "pearl". According to Chazo's records, a "pearl fetus" was born in Greece in 1964. In fact, these are all organic lumps mainly made of calcium carbonate.

Reno Amore's research proves that mollusks secrete the most "pearls", and only mollusks can secrete pearls in the sense of jewelry and jade science. Therefore, the so-called pearl in jewelry science should be defined as a hard substance with calcium carbonate as the main component and a smooth pearl layer outside (Figure 22-1-kloc-0/,Figure 22- 1-2). "Smooth nacre" is particularly important. Because only in this way can pearls meet the four elements of jewelry and jade science, not all blocks with calcium carbonate as the main component can be named as "pearls" in the sense of jewelry science. People in the jewelry industry are used to calling "pearls" without pearl luster as "bone pearls", and many of the generalized "pearls" mentioned above belong to the ranks of "bone pearls".

Fig. 22- 1- 1 sand and other foreign bodies invade shellfish to form pearls.

Fig. 22- 1-2 Pearl formation by trematode parasitism

1-epithelial cells on the lateral surface of the mantle; 2- blood cells; 3- nacre; 4- pearl capsule epithelial cells; 5- connective tissue; Residual nucleus of 6- trematode; The throat of 7- trematode; 8-trematode digester