Hi, in the sci-fi story I'm writing there is a planet rich of carbon-like element(let's name it X element), that must posses this characteristics: 1 - X element common form is stable(non-radioactive) and it's like graphite - soft and with dark metallic shine. while it's hardest allotropic form is unstable crystals that emits radiation - is this possible and how? 2 - some bonds of the X element with other known elements from the real periodic table makes high-temperatures(-10 or -20 degrees celsius) super conductive materials - which of the known elements will be suitable for such bonds? 3 - the life forms on the alien planet are almost all based on the X element(not carbon) - knowing that the X element is similar to the carbon will the alien life look like the earth life(in my story I have mostly mushrooms, insects, invertebrates, moss and lichens)? What properties the X element should have in order to suit all the characteristics above, how should I present this element in a scientific plausible way? Thank you!