I’ve never seen this before anywhere I’ve lived. I’m using plastic ice trays and a small Tupperware container that makes a perfect sized block for a large tumbler. This only just happened today. I didn’t wash them between uses so I don’t think it’s a contaminant. Also it only happened to 2 the first time and 1 the second. They’re very thin and about a quarter inch tall. Nothing is dripping down. So what’s causing it?
Previous threads:
Ice cube tray stalagmites
Stalagmites in ice cube tray?!
WIERD ice-cubes.
Spikecicles (reprise)
The surface of the ice cube starts to freeze and leaves a small hole of unfrozen water. As the water inside the cube freezes, it expands and forces the water inside the cube up through the hole, forming a mini ice volcano. This eventually also freezes solid, forming your little stalagmite. They are more likely to form if you use distilled water. Ice will form around the impurities in non-distilled water and will often plug the hole before the ice spikes can form.
Here is an interesting video of an ice spike forming: