Very massive stars are cosmic "rock stars" that live fast, die young and leave black holes in their place. During this transformation, they may vomit out more stellar material than we knew.
When it comes to star formation, not all galaxies are the same. Some are quenched, meaning they've depleted their star forming gas and form very few new stars. Some, like the Milky Way, are typical and form stars at an average rate. But some are extremely active, and form stars so readily they're called starburst galaxies.

