In the ocean there are a lot of different salts- like the familiar table salt we call sodium chloride (NaCl). Other salts include potassium (also found in bananas), calcium (like in our bones), magnesium, and sulfates (what makes hot springs smell like farts). They are all really important. For instance Calcium is used by snails, crabs and even some seaweeds to build their shells. Magnesium too!