"Our Earth consists of silicate rocks and an iron core with a thin veneer of water and life. But the first potentially habitable worlds to form might have been very different. New research suggests that planet formation in the early universe might have created carbon planets consisting of graphite, carbides, and diamond. Astronomers might find these diamond worlds by searching a rare class of stars.
"'This work shows that even stars with a tiny fraction of the carbon in our solar system can host planets,' says lead author and Harvard University graduate student Natalie Mashian.
Press Release: https://www.cfa.harvard.edu/news/2016-12