Galaxy that has a dense core of stars and has spiral arms

All galaxies have a dense core of stars. Spiral galaxies, however, have arms that are often visible. There are two kinds of spiral galaxies: barred, where there appears to be a line running from arm to arm through the core, and ordinary, where there is no bar. @Badbunnyhunny

It is evolution, because we all have some of the same traits like eye color or shape or ears.

Can you write it in english