AKA “It’s ice, Jim, but not as we know it.”
Water is one of the weirdest molecules in the galaxy. H2O disassociates relatively easily, so in many cases it’s more a cloud of loosely associated hydroxide and hydrogen ions than a bunch of complete molecules.
Which leads to its other interesting properties. It’s a near-universal solvent, for one; almost everything that exists on Earth will dissolve in water, given enough time. Its state changes make other molecules stare; the various ionic bonds in any body of water keeping it liquid when most other molecules that size would be a gas, and still liquid at temps that freeze metals solid. On top of that, under Earthlike conditions, it’s most dense as water a few degrees above freezing, not as ice. Ice floats. These three properties – solvent, broad liquid phase, and ice floating instead of freezing water from the bottom up – are critical to life as we know it. I’m not going to rule out the possibility of alien life not based on water (after all, alien), but based on everything we know about physics and chemistry to date, it seems highly unlikely.
Water is so very, very unusual a molecule that we keep studying it, trying to figure out if we really know what we think we know about it. For example, theoretically, ice shouldn’t be as rigid as it demonstrably is. Perfect ice should be able to bend; 15% elastic strain, says theory. Only in RL we see it shatter at less than 0.3%, because real ice has imperfections everywhere.
Okay, said some scientists at Zhejiang U. What if we grew some ice without imperfections?
The experiments took water vapor, electric fields, an ultracold chamber, and temps down to 150 degrees C. Do not try this at home. But they got a microfiber of ice, and they bent it. Into an arc. Almost a circle. Estimated elastic strain, about 10.9%.
Bendy ice. The image makes my brain go, “…Nope.” But the idea that ice can bend, if it’s pure enough… wouldn’t that make for some interesting fantastic fiction? The researchers involved are talking about low-temp sensors made of ice. In a fantasy world, an iced-over lake wouldn’t have to melt to be a death trap. It could be like walking on rubber….
And if you want something even weirder, in 2019 scientists confirmed that under enough pressure, you can make ice that’s thousands of degrees hot.
(They call it Ice XVIII. I see SF book titles now.)
They speculate that this may be why Neptune and Uranus have such weird magnetic fields – that they have a mantle of solid hot superionic ice, which is highly conductive, and not the ocean of water and ammonia previously theorized.
Any way you slice it, if your fantastic characters are going to be working with ice, check out its crazy RL properties.
You may find something really cool.