calcium carbonate

How is calcium carbonate extracted from sea water?

Ask a clam.

Or ask Professor Hilbertz. (I’m not going to fully vouch for this, since the remainder of the website seems a bit cracked, but …)

http://www.celestopea.com/seament2.html

Inorganic calcium carbonate precipitation in seawater occurs when temperature increases. A temperature increase results in carbon dioxide escaping to the atmosphere, thereby reducing the solubility of the dissolved calcium. This happens in shallow water. In the deep sea, lower temperatures and increased pressure increase the solubility of calcium.