Seashells

1) What are seashells made of?
2) How do mollusks make their shells?
3) What is the difference between bivalves and gastropods?
4) How many types of seashells are there?
5) What is the biggest seashell in the world?
6) What is the smallest seashell in the world?
7) Where can I find seashells?
8) How can I tell if a seashell is alive?
9) How do I clean a seashell?
10) What should I do with my seashells after I collect them?