A NASA spacecraft has returned asteroid samples that hold not only the pristine building blocks for life but also the salty remains of an ancient water world.

Samples of Bennu were brought back to Earth by NASA’s OSIRIS-REx spacecraft in 2023. Now, a pair of newly published papers reveal that the samples contain precursors to life that formed in a watery environment—a watery environment very similar to the one that prevailed on Earth before life emerged up to four billion years ago.

Scientists from NASA and other institutions who have been analyzing the Bennu asteroid sample that returned to Earth last September found molecules, including amino acids, which are essential ingredients of life as we know it.