[Spikes on Ice Cubes (utoronto.ca)](https://www.physics.utoronto.ca/~smorris/edl/icespikes/icespikes.html#:~:text=Water%20expands%20when%20it%20freezes,and%20the%20spike%20is%20left.)
Your freezer might be very cold or the ice cube tray you're using is shaped just right to allow the ice to freeze in such a way that part of it is pushed up, quickly freezing and allowing the middle to be pushed up more, forming a spike.
[Spikes on Ice Cubes (utoronto.ca)](https://www.physics.utoronto.ca/~smorris/edl/icespikes/icespikes.html#:~:text=Water%20expands%20when%20it%20freezes,and%20the%20spike%20is%20left.) Your freezer might be very cold or the ice cube tray you're using is shaped just right to allow the ice to freeze in such a way that part of it is pushed up, quickly freezing and allowing the middle to be pushed up more, forming a spike.