i want to know about shells, how shells are formed, how shells are trnsformed tobeach sand and the uses of she

Answer 1

The shell will grow over time as the animal inside adds its building material to the leading edge near the opening. This causes the shell to become longer and wider to better accommodate the growing animal inside. A mollusc shell is formed, repaired and maintained by a part of the mollusc called the mantle. Injuries to or abnormal conditions of the mantle are often reflected in the shell they form and tend. When the animal encounters harsh conditions which limit its food supply or otherwise cause it to become dormant for a while, the mantle often ceases to produce the shell substance. When conditions improve again and the mantle resumes its task, a "growth line" which extends the entire length of the shell is produced, and the pattern and even the colors on the shell after these dormant periods are sometimes quite different from previous colors and patterns.

The majority of shells are made of nacre, an organic mixture of outer layers of horny conchiolin (a scleroprotein), followed by an intermediate layer of calcium carbonate (CaCO3) as either calcite or aragonite in the form of platy crystals. Shells of the class Polyplacophora are made of a softer calcium carbonate compound called chiton.
The bright white sands found in tropical and subtropical coastal settings are ground-up limestone. Arkose is a sand or sandstone with considerable feldspar content which is derived from the weathering and erosion of a (usually nearby) granite. Some locations have sands that contain magnetite, chlorite, glauconite or gypsum. Sands rich in magnetite are dark to black in color, as are sands derived from volcanic basalts. The chlorite-glauconite bearing sands are typically green in color, as are sands derived from basalts (lavas) with a high olivine content. The gypsum sand dunes of the White Sands National Monument in New Mexico are famous for their bright, white color. Sand deposits in some areas contain garnets and other resistant minerals, including some small gemstones.

Answer 2

Shells are formed by chitin which is produced by the animal. Once the animal dies the exoskeleton(shell) is left behind and eventually washes up on the beach.

Answer 3

Here are some sites where you can find a lot of information about shells:

http://www.seashell-collector.com/

http://www.conchologistsofamerica.org/home/

http://www.manandmollusc.net/

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