Our automatic ice maker is on the fritz, so we’ve temporarily reverted to making ice in conventional trays. But, imagine our delight at opening up the freezer and finding this!

Several of our ice cubes apparently formed with long spikes on top. This is really *not* what you expect when you start out with liquid water in an ice cube tray.

Snowcrystals.com has a fairly detailed explanation of how these things form, and it’s documented elsewhere as well. (Roughly speaking, supercooled water is pushed up through a hole, somewhat like magma forming a volcano.) It’s relatively easy to form these in your freezer if you start with distilled water, but occasionally– as in our case –they do occur with regular tap water.