I had been cutting up a big watermelon and had a little bit left that wouldn't fit in the container. I thought, hey, watermelon is mostly water, I bet you could mash these up, freeze them, and make tasty ice cubes. Thus, these were made.
They look really pretty and I thought they might give a tasty hint of flavor to a glass of water, like cucumbers or lemons. Great in theory, but terrible in practice.