Ice cubes made in a standard mold had 2 1/2 inch "icicles" pointing up (not straight) with nothing dripping??

Question

How were these formed? There were three of them, each on seperate cubes, and they weren't straight up or formed by dripping water. The water was purified Ozarka brand. I make cubes all the time and have never seen this phenomenon. Thanks!

Answer 1

the outside freezes, leaving liquid in the middle.

however, as that outside shell gets thicker, the ice expands, and some of the center liquid must go somewhere.

the weakest point is the center of the top, which gets pushed up, creating the mound that you see.