Avi Loeb, an astrophysicist at Harvard University in the US, has published a press release claiming that some of the 700 or so spherical metallic fragments (spherules) he recovered from the bottom of the Pacific Ocean, just off the coast of Papua New Guinea, are from beyond the solar system.

The discovery was quite interesting because, although such spherules are distributed globally, it is not easy to recover them from the depths of the ocean bed—requiring a dredging operation with a powerful magnet. But Loeb has speculated that the spherules may be related to the passage of an interstellar meteor, IM1, which burned up over the South Pacific Ocean in January, 2014. He has even hypothesized that the spherules are actually debris from an alien spacecraft. I commented at the time that I'd need firm analytical evidence to accept such interpretations.

Loeb has now provided a very detailed set of analytical data of 57 spherules in an article submitted to a journal.