Here is a pic of a Stainless Steel wedding ring and a 1954 silver quarter after being poorly stored together for about 6 months. I found both last year metal detecting the west coast beaches of Florida. When I found the ring it looked "new" and the quarter had beautiful light brown patina. After finding them and a bunch of other "OK" targets early last year, I stored them in a sealed plastic bag. In the fall, I opened the bag and discovered that the SS ring almost welded itself to the silver quarter. Parts of the edge of the ring are now missing and particles are welded to the coin. The collector value of the ring and quarter are gone. The ring is now worthless and the quarter is only worth it's spot silver value.
What happened? I believe that there were sea salt remnants of the ring and coin and the sealed plastic bag sealed in moisture. In physical contact, the salt and moisture created the ideal conditions for an electrolytic action to take place and, in this case, material from the stainless steel ring was transferred to the coin.
This experience has taught me the value of washing and drying well my metal detector finds and the need to place valuable finds in separate envelops.
For anything you want to save that's been in salt water, let the items sit in fresh water for a week, dump and do it again. Use an aquarium hydrometer to test the salt content of the old water after about the 3rd water change. It's ok after sitting a week with zero salt content and store everything dry.