Hello! I'm looking for information on the sources of calcium for modern cephalopods. Cuttlefish, Nautilus and Spirula need a large amount of calcium for the development of their shells. Whether they receive calcium from the food or absorbed it from seawater? The first version (with food as a source of calcium) seems more logical for me, but this is only an intuitive hypothesis. Could you help me with references to the literature containing such information?