The JWST has detected a key building block of life at the dawn of the universe, upending what we know about the first galaxies.

The discovery — a cloud of carbon in a distant and compact galaxy as it appeared just 350 million years after the Big Bang — marks the earliest detection of an element other than hydrogen in the universe.

Astronomers classify elements heavier than hydrogen and helium as metals. That’s because, aside from hydrogen and trace amounts of lithium, these elements were forged inside the fiery furnaces of stars and distributed throughout the universe by star explosions called supernovas.

This process of heavy element production and seeding was once thought to take many star lifetimes before elements heavy enough to form planets were widely available. But the new discovery has challenged this preconception.