Rigid skeletons are formed from materials including chitin (in arthropods), calcium compounds such as calcium carbonate (in stony corals and mollusks) and silicate (for diatoms and radiolarians).
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c. he should write down data clear, step-by-step instructions as he goes along
Answer: Chemical weathering decomposes or decays rocks and minerals. An example of this is water and limestone. Organic weathering happens when plant break up rocks. One the rock has been weakened and broken up it is ready for Erosion. This happens when rocks are picked up and move usually by water. Mechanical weathering breaks up rocks, this usually happens when water gets into cracks, freezes and expands the rock
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