We already know how pearls are born: when a foreign object is trapped in the clam’s flesh, in order to relieve the pain, the clam will quickly secrete nacre to wrap its sharp edges and corners, forming a pearl sac, wrapping a Layer after layer, as time goes by, the foreign matter is covered with thick nacre, until it forms round and beautiful pearls. The round pearls no longer have sharp edges and corners, so they will not hurt the clams.
But how does the clam wrap its oddly shaped foreign body into a spherical shape?
Observing the pearls produced by different species of clams, it was found that the thickness of the nacre of these pearls was not the same. Moreover, due to the different shapes of the foreign bodies in its core, the clam will evenly secrete and deposit nacre in different positions when it first wraps the foreign bodies, making the early nacre structure irregular and strange in shape. But the resulting pearls retain their nearly perfect spherical shape. How do clams do this? How do they know that they should secrete less nacre in places with protruding edges and more in sunken areas? For centuries, people have puzzled over the clam’s ability to “calculate” with astonishing accuracy.
Recently, a research team in Australia revealed the secret. They collected a batch of pearls made of mother-of-pearl martensii from pearl farms along the eastern coast of Australia, cut them into sections with a diameter of 3-5 mm, polished them, and examined their fine structures with an electron microscope. They calculated that Pearl oyster martensii can secrete an average of 2,615 layers of nacre in 548 days. They cover the nacre neatly and precisely with foreign matter like soldiers, with organic matter sandwiched between layers. There are interactions among the layers, the layers with the same rotation direction attract each other, and the fractures with different rotation directions fit together perfectly. This process causes the entire tissue to gradually converge, and over time, flawed structures eventually become regular and homogeneous.
As for how many layers of nacre should be secreted in different regions, molluscs follow the “pink noise law”. Pink noise is the most common noise in nature, and its melody has certain rules: its energy is inversely proportional to frequency, the next tone is affected by the previous tone, and the same melody will be repeated every once in a while. People will have the same regular phenomenon – a series of seemingly random events are actually interrelated, each new event is affected by the previous event, and things develop in a cyclical way – as the “pink noise phenomenon” . There are “pink noise laws” in many natural and man-made phenomena, such as birdsong, insects, tides, and wind blowing are all pink noises, the conduction of brain waves and the regular beating of the heart also follow the same law, even the classic The melodies of music and the activity of economic markets show similar regularities…
In the case of pearls, the formation of nacres of different thicknesses may appear to be random, but are actually dependent on the thickness of the preceding layer—if When one layer is extra thick, the next layer will be a little thinner, and vice versa. After repeating this process many times, the finally produced pearls have the same number of nacre layers in different positions, but different thicknesses, and finally form a round and symmetrical structure.
Structural complementarity and pink noise – these two abilities of the clam ensure that the pearl maintains a similar average thickness as it grows through its thousands of layers, giving it a round, uniform appearance. Without such constant adjustments, pearls could, like layered sedimentary rocks on the surface, fail to heal or even enlarge small imperfections that prevented them from growing into a spherical shape, eventually becoming oddly shaped.
In fact, clam-made pearls are an even more remarkable material than we previously thought. They are composed of calcium, carbonates and proteins, yet are thousands of times stronger than the materials of which they are made. These materials produced by humble creatures are more easily and better than materials produced by humans using any technology to achieve ultra-light and ultra-tough properties. By learning how clams make strangely shaped foreign objects into intricately structured pearls, people could make supermaterials with better properties, such as more energy-efficient solar panels or tougher, heat-resistant materials that can be used as outer shells for spaceships. Material.
