Shells...I have a bowl set up just like this! Will add the strand of pearls, I also have, but didn't think to put them in the shell display like they have here. Will fix that later today because I love what they add to the look :)
I plan to paint the back of the two bookshelves the same blue as the wall too. Although, I saw two photos in which the bookshelves back were painted a darker blue, and were a distressed white, respectively.