Ice Spike.

Ever got an ice spike when making ice using those ice cube trays? Ever wonder why they happen and how to make more of them? Ken Libbrecht of Caltech has the answer:

To see your own ice spikes, make ice cubes in an ordinary ice cube tray, in an ordinary household freezer, but using distilled water, which you can buy in most supermarkets for about a dollar a gallon. We've tried several different freezers, and almost always got some ice spikes to grow.

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