How do Some Creatures Make a Shell on their Body?

            You must have heard the sound of conch (shank) being blown during worship in the temples. You must have also seen big and small conches on the seashores and on the riverbanks. Some conches are so small that they can be seeing only with the help of a magnifying lens. While there are others that are as big as measuring up to 120 cm.


            Do you know what these conches are and how they are formed? They are the body shells of aquatic creatures. These creatures are called mollusks. The scientists have so far studied approximately 60,000 species of the mollusks. As the mollusk grows; the outer shell also grows and becomes harder. They are made up of calcium carbonate lime. The mollusk collects lime form seawater and deposits it in its outer shell. When the mollusk dies, the shell floats and comes to the surface of water.

            The shell of the mollusk has three main layers. The outer layer of the shell is made up of smooth material like the oyster and contains absolutely no lime. The middle layer is made up of calcium carbonate. The inner layer comprises man thin layers, which are made up of oyster-like material and calcium carbonate. Conches come in many colors. Some of them have pattern of stains and stripes on them. These stains, colors and stripes have their origin in some colorful materials present in the glands of the mollusk, and these colors, stripes and stains enhance the beauty of the conches.

            The conches protect the mollusk living inside. When the mollusks finally die, the shells become very useful to us in many ways. In early times, people used mollusk shells (cowries) as coins.

            Small conches are even used in necklaces, and as decoration pieces in homes. Mother-of-pearl buttons are made from small shells. Aquatic animals with shells have existed for billions of years. After their death, these shells are deposited on the seabed, which form limestone rocks.