Seashells, which serve as the external skeletons of some sea animals, are made mostly of calcium, like other skeletons. Seashells that have been broken down into grains help make up the sand found on tropical beaches, ac... More » Pets & Animals Marine Life

A mineral is made up of one or more elements, such as iron or gold, that are fused together. A rock is classified as igneous, sedimentary or metamorphic based on how it was formed. More » Science Earth Science Geology

The game of Mancala is believed to have originated in Africa. The earliest games were played by scooping holes from the earth and using pebbles or seashells as the moving pieces. Over time, game boards were created, and ... More » Hobbies & Games Board Games
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Seashells, which are the exoskeletons of mollusks such as snails, clams and oysters, form from the bottom up starting with mantle tissue located underneath and in contact with the shell. The mantle secretes proteins and ... More » Pets & Animals Marine Life

Seashells are exoskeletons of marine invertebrates such as mollusks and sea snails, and they grow from the inside out or by depositing new material at the edges, according to Scientific American. Two common types of seas... More » Pets & Animals Marine Life

Seashells, often found washed up along the shores of oceans, are the skeletons of marine animals known as mollusks. Mollusks have exterior skeletons, whereas many mammals, including humans, have interior skeletons. The s... More » Science Earth Science

Some unusual types of sea animals include the siphonophores, colonies of animals that superficially resemble jellyfish; sea anemones, animals that look like flowers; and the sea mouse, which is a bristly worm. Siphonopho... More » Pets & Animals Marine Life