Carbon-rich planet slice illustration (IMAGE) Arizona State University Caption An unaltered carbon planet (left) transforms from a silicon carbide dominated mantle to a silica and diamond dominated mantle (right). The reaction also produces methane and hydrogen. Credit Harrison/ASU Usage Restrictions with credit License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.