What are these purple (dust) clouds?
This image is from the Illustris simulation (GZ blog post on it here), which is a very cool project 😃
In this sim, blue signifies young stars, and yellow older ones. While Illustris does include dust, it's not localized, just a 'screen' over the whole (simulated) galaxy. So blue blobs are indeed (simulated) star-forming regions, but they're like real ones only in some respects. For example, in real star-forming regions, there will be supernovae every now and then, but Illustris does not include such fireworks.
Happy hunting! 😄