“Solid ice is stable to over 200 GPa and 4400 K in a body-centered cubic structure, near the melt boundary in water-rich Neptune-like planets. This may be responsible for the increased electrical conductivity that may promote the generation of multipolar magnetic fields. Due to the fluidity of the protons in Ice XVIII, and in contrast to the low-pressure ices, this ice is likely to be black. The oxygen ions form a close-packed structure with 12 nearest neighbors to each side, filling 74% of the space. This ice may be considered as a new state of matter, solid and liquid, at the same time, similar to a metallic structure but with free protons rather than electrons. It has been suggested that suitable conditions for Ice XVIII lie deep inside the watery giants Uranus and Neptune and may be common throughout the Universe.” – Martin Chaplin, Water Structure and Science