Astroboffins think strangely porous boulders found on asteroid Ryugu may be the stuff of proto-planets

Pumice-like stuff spotted by Japanese Hayabusa2 probe would float on water

Asteroid Ryugu, the rock from which Japan’s Hayabusa2 probe brought home some samples, is home to highly porous boulders that might just have been the stuff of which planets were made.…

from The Register