Don't worry it isn't anything to freak out about. It is not salt deposits but it is a form of calcium. They are actually small crustaceans. The white things are their spiral shells. These animals are called Spirorbids. They are small filter feeding animals that show up in newly established reef tanks. I had a ton of them in my tank, but as soon as all there food supply is gone they will dissapear. My three words of advice when it comes to maintaining a reef tank is be patient, read all you can, and watch your tank closely for any changes-all the time.