1 st post general questions

[jonathan h]

Hello, this is my first post.  My dad has a very nice sea shell collection that was my grandparents (Charles & Violet Hertweck) and I am posting questions for him.  My grandparents have their shells identified and put in a small box with a little index card that has the species name and I believe which year and location of the find/purchase.  Most of the shells have what appears to be a thin foam that they rest on.  We have some shells that do not have this "foam" and were wondering if there anything special about the foam.  Also if there is anything that we need to avoid putting the shells on or near.  Like chemicals in plastic or foam.  The shell collection was in our house and we had a house fire.  The shells were fine and my dad went through and cleaned most of them up, from the dirt because when had to store them while the house was rebuilt.  What should we clean them with?  Is there something we can put on the shells, like a wax or something to protect them more?  Any tips or advice would be greatly appreciated, as we would like to keep this collection as nice as possible for the years to come and keep this in the family for generations to come.