Water is one of the few substances on earth that takes up more volume as a solid than as a liquid (roughly 8% more), leading to the formation of strange structures known as "ice spikes".
Image Credit: Wikipedia user Priesemut24, licensed under CC BY-SA 4.0
July 30, 2015
You might recognize these as much larger versions of the spikes that sometimes pop up on your ice cube tray in the freezer. When water reaches its freezing point, its molecules tend to latch onto one another at an angle of about 109.5 degrees, the interior angles of a four-faced pyramid (a tetrahedron). This property is responsible for everything from the complex and beautiful shapes of snowflakes to the jagged and triangular shape of the spikes you see here, which occur when liquid water from the interior is forced up through a hole in the frozen surface.