A fairly nice display of shells. Note the watercolor tucked into the 3rd shelf; I would display a few more things that are not shells - a lighthouse, a jar of seaglass, a pelican, a sailor's knot or a buoy - to give a little relief.
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.
Stacked Sea Treasures,we went to Pottery Barn,several years ago,they had wonderful,washed white candle stands, and the candles were in different sea shells molds. Needless to say,we spent moree than we had planned but it's still beautiful.