Changes

Objects which are '''calcareous''' in nature are composed of or contain [[calcite]] or [[calcium carbonate]].  [[Chalk]] and [[limestone]] are calcareous, being composed of calcium carbonate.  Certain groups of sea creatures ([[calcarea]], [[phytoplankton]], and [[sea urchin|sea urchins]] for example) have calcareous skeletal structures, which accumulate on ocean floors, and is a major factor in how [[coral]] is formed.

Objects which are '''calcareous''' in nature are composed of or contain [[calcite]] or [[calcium carbonate]].  [[Chalk]] and [[limestone]] are calcareous, being composed of calcium carbonate.  Certain groups of sea creatures ([[calcarea]], [[phytoplankton]], and [[sea urchin|sea urchins]] for example) have calcareous skeletal structures, which accumulate on ocean floors, and is a major factor in how [[coral]] is formed.