Large Glass Vases - What could I put in them?

Hi everyone,

This is my first time on this site so I hope my question is appropriate. I have acquired two large glass vases (see through http://www.hallomall.com/home-decor/vases/glass-vases.html) and want to put something in them other than flowers! They are very big, any suggestions? I have bought 200 multicoloured glass pebbles, but they don't even fill one of them half way, so want ideas on what I could put in the rest of the vase/ what I can put in the other? Thanks :)
P.s (the glass vases are to go in the living room as decoration)