When I was in 7-8 grade I saw (as anyone else) the StarWars episodes. After this experience, I still had lots of unanswered questions. For example, what is carbonite - the black material they used to pack Han Solo in Episode 5? Hmmm... I had that question stuck in my head for a while.
Maybe I don't ask myself these questions today, but I was surprised to find out about a new amorphous form of CO2 - called a-CO2, or amorphous carbonia. This material is nothingg more than regular CO2, but in an amorphous solid state. Let's remember that the carbon's cousin in the Periodic Table (Si) also has an amorphous form of its dioxide, called quartz glass - the special type of glass used in halogen light bulbs. In turn, a-CO2 also forms some sort of carbon-based glass.
At present, a-CO2 is a curiosity because it cannot be tested or used outside the pressure chamber. The CO2 that in these extraordinary conditions takes up a chaotic "amorphous" structure, becoming glass, reverts to orderly molecules of CO2 under decompression.
So far, this material was produced by exposing regular CO2 dry ice to half million atmospheres, but it might be possible that the same material is (meta)stable at room temperature and pressure. But that's an open question, along with the similar question around metalic hydrogen.