These are all good sources of many minerals, especially iodine.
These must be eaten very fresh. For this reason they should be obtained alive when they should move actively.They are killed by dropping into boiling water. The head sac and the intestine needs to be removed and discarded. The gills are discarded after cooking. They are best cooked by boiling or steaming as they tend to dry out rather easily.
Prawns and shrimps
These must be cooked fresh, within a few hours of being caught as they deteriorate rapidly. The heads and the shell are removed before eating. The shells can be eaten and can be a useful source of calcium.