Giant planets like Neptune may contain much less free hydrogen than previously assumed. Researchers drove shock waves through two different types of plastic to reach the same temperatures and pressures present inside such planets, and observed the behavior using ultra-strong X-ray laser pulses. Unexpectedly, one of these plastics kept its crystalline structure even at the most extreme pressures. Since the icy giant interiors are made up of the same components as the plastic, planetary models may need to be partially reconsidered.