[Smokin' Joe]

Wait. I thought CO2 in seawater provided part of the CO3 that, when bonded with the Calcium cation makes up Calcium Carbonate--the material found in many little sea critter shells.

The other 'biggies' are chitin and silica (silicon dioxide).

Maybe the oceans are suffering from a Calcium deficiency...

[justa-hairyape]

Shh... That is the dirty little secrete no one is supposed to know. Most skeletal structure requires carbon, which can enter the oceans from dissolved CO2.