calcium carbonate and oyster shell calcium
 

calcium carbonate from oyster shells and just pure carbonate calcium ( I have seen on bottles of calcium) are the same or different. I am a little confused. I have always assumed that if the calcium is from oyster shells the lable says so. But now I am not sure. if the bottle says carbonate does that mean its from oyster shells.

this can all be so confusing...

any help on clarification would be greatly appreciated.