Almost every object in this photo is a galaxy. The cluster centre shows two yellowish giant elliptical galaxies which dominate the core region. Almost all the light sources seen in this image, apart from the bright blue foreground star, are galaxies within the cluster

Most galaxies in the Coma and other clusters are ellipticals, while most galaxies outside of clusters are spirals

Coma had generally been thought of as a rather structureless and well evolved cluster. X-ray images however show clear signs of complex substructures in the hot intracluster gas

This probably indicates that the cluster has a lively recent history, and has swallowed a number of smaller clusters within the past few billion years