A Molecular Code Turns Water into Ice?

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In a discussion about the genetic code being a real code, that included nature's inability to produce such codes I was told there is a molecular code that turns water into ice @ zero C.

And here I thought it was all just physics. The surreal event starts here with the question:

Is H2O a code?

I responded by saying that H2O is the symbol for the chemical formula of a water molecule. So yes, writing H2O is a code for a water molecule.  Turns out that wasn't what she was talking about:

I was talking about the molecule itself, not the symbol.

After checking several times to see if I read that correctly I said- The molecule is not a code. It doesn't fit the definition. Earlier I had linked to the wikipedia entry on codes so at least my dimwitted opponent would understand the context and to show the genetic code is a code in the same sense as human codes. She didn't read it.

Brace yourselves for the next part. The response to my saying the molecule is not a code was:

Really? So the fact that it crystallized at zero C is just magic? Or is their a built in molecular code?

BWWWWWWAAAAAAAAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA

Physics be damned- it is either magic or a molecular code. Well, to this dolt physics is magic.

A molecular code kicks in @ zero C? What are the symbols and what do they represent? If only my ignorant opponent would have read the Wikipedia entry on codes. That would have amounted to its total education in the subject and she wouldn't have made such a stupid mistake.