>>48952398>>48954114>>48954420I'd argue it's mercury.
Mercury goes by the archaic name of quicksilver, because it is like silver in appearance, but it is liquid at room temperature. "Silver water" conveys the same concept as "quick silver".
If it was silver, it would have to be melted with high heat. The substance in the film is seen flowing through channels and collected in buckets but it is not actively heated by anything at any point. The big bad does inexplicably control Heatran, though, which may be telling.
Mercury isn't solid at room temperature, but after Arceus is submersed in it, a battery of Pokemon using Ice Beam rapidly chill it to below its freezing point.
Mercury's freezing point is something insanely cold like -40, so I don't exactly buy that it can be flash frozen and kept that way without it beginning to thaw almost instantly, especially when characters walk on it moments later. I still buy it over 1,000 degree molten silver, though.
Or perhaps everyone is wrong and it's actually gallium. Or most realistically, some mercury and/or gallium alloy that has a melting temperature closer to room temperature.
