Plastic ice seen with elastic-neutron scattering

While on Earth we mostly encounter the hexagonal, crystalline ice (like ice cubes, glaciers, snow), there are at least 20 other known ice phases, many of which have merely been theorised to exist in particular temperature and pressure conditions. One of those is plastic ice, which differs from "conventional" ice in the sense that molecules can rotate in their positions as in liquids, yielding a substance that is intermediate between a liquid and a crystal, exhibiting peculiar elasticity.

The conditions that are intrinsic to plastic ice are observed in planetary interiors, which means that it may be formed within icy worlds like Neptune and Jupiter's moons, including Europa.

Baptiste Journaux of the University of Washington claims that plastic ice may have existed in the early formational stages of Europa, Titan, and other icy moons in our solar system, before the water had escaped from the high-pressure interiors. This could influence our understanding of the geodynamics of icy planets in general and the differentiation processes of large icy moons.