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\subsubsection{Age vs Spiral arms}  How do spiral arms form in a disk - are they present from early formation or do spiral galaxies begin their lives as Lenticulars? Can the number of spiral arms change as the galaxy ages?   \citet{Elmgreen2014} \citet{Elmegreen2014}  found stuff \subsection{Morphological changes over time}  Current observations suggest that a large fraction of originally-disk galaxies can change morphology into elliptical shape. Does this transformation occur around the same time for all disks? Can disks spontaneously lose their disk structure over time, or does it have to undergo an interaction with another galaxy to transform? Is there a third option? Are there any very old disk galaxies, or do they all lose their disk structure at some point?