Elliptical galaxies appear to be smooth and featureless, yet surprising properties are hidden inside them.
Many are thought to have formed early in the universe's history in massive bursts of star formation;
after a while, the star formation stops and the galaxy evolves up to the present day.
But other theoretical models suggest that at least some elliptical galaxies are forming by the merger of
two spiral galaxies, which could be an on-going process.