My pet (hyuck) theory is:Cats see into the UV range.Anything capable of refracting light is potentially mesmerizing to them, they would be seeing 'colors' that we cannot perceive.I feel this also explains a lot of the times cats seem to ... just be staring at a wall, for no apparent reason.... that or maybe he's just a silly bean and really appreciates ice cubes, on a conceptual level.
I had a cat that would do this also. He was listening to the slight crackling sound the ice made as it melted.
Second post I see with the same structure and text, but a different cat staring at an ice cube.Something tells one of them is just someone taking a photo of a cat next to an ice cube and posting for karma or whatever...
More precisely, cats are pure agents of entropy and appreciate game when they see it