as well as shells, what other marine organisms need carbon and calcium? im nice so imma give 65 points :)

Photosynthesis by tiny marine plants (phytoplankton) in the sunlit surface waters turns the carbon into organic matter. Many organisms use carbon to make calcium carbonate, a building material of shells and skeletons. Other chemical processes create calcium carbonate in the water.

Explanation:

o conteúdo de calor de um sistema é igual à entalpia apenas para um sistema que é constante