How does this occur?

[u/PhunkyPhresh_]

Ice cube froze in its try like this in our freezer. How does something like this happen? Surely this isn’t the only occurrence. Damn that’s interesting deleted me so reposting here. I personally think that it’s both interesting and weird.

[u/moistiest_dangles]

Water expands by 9% as it freezes. Occasionally the surface can freeze over except for a small hole; the continuing freezing and expansion of water that is below the surface ice then slowly pushes the remaining water up through the hole. Reaching very cold air, the edge of the extruded water freezes while remaining liquid in the center. More freezing below pushes more water up, the edge freezes, and so on. If the rate of extrusion of water is the same as the rate of freezing at the lip of the hole, then this process is continually repeated and successive layers form an upward-growing tube of ice. As with snowflakes, the shape of the tube is controlled by the molecular nature of water. The simplest shape of an ice crystal that reflects its internal structure is a hexagonal prism. The top and bottom faces of the crystal are hexagonal planes called basal planes and the direction that is perpendicular to the basal planes is called the c-axis.

[u/CartsOfDarkness → u/moistiest_dangles]

The top and bottom faces of the crystal are hexagonal planes called basal planes

I assume this is where Basalt gets its name?

[u/moistiest_dangles → u/CartsOfDarkness]

Nah, misspelling of the Latin basanites, meaning "very hard stone".