I suppose the shapes have a lot to do with the medium - ie the metal plate and its consistancies more so than the actual reaction of the salt to the soundwaves - as it is the vibrational patterns of the plate that marshals the salt - if you will.
Dont know this for sure - just a guess..
peace
ausser.
Will we march only to the music of time...?
Or will we march to the soul-saving music of eternity?
MLK Junior - Strength to Love 1963.