Calcium carbonate can also spontaneously precipitate out of solution, but it takes greater extremes of temperature, concentration, or other chemical changes. Sh

Calcium carbonate can also spontaneously precipitate out of solution, but it takes greater extremes of temperature, concentration, or other chemical changes. Shellfish increase the rate at which dissolved calcium carbonate converts to solid calcium carbonate. That action increases the rate at which trapped carbon can be returned to the atmosphere via subduction and volcanic emissions, which means a higher equilibrium concentration of atmospheric CO2 and a warmer planet than we would have if the oceans were lifeless.