What significant role do the short-lived O and B stars play in cosmic element formation?

They are the primary factories for synthesizing and enriching the interstellar medium with heavy elements up to iron.

While O and B stars live briefly, their intense, rapid lifecycle is crucial for the chemical enrichment of the cosmos. Their high mass enables them to reach the necessary core conditions not just for hydrogen fusion, but subsequently for fusing heavier elements, moving up the periodic table sequentially, including helium fusion, and continuing up to elements like iron. This complex, high-energy nucleosynthesis occurs quickly within these massive stars. Upon their inevitable, often catastrophic demise, these newly forged heavy elements are violently ejected into the interstellar medium, seeding the subsequent generations of stars and planets with the necessary raw materials for rocky worlds and life.