How do these work?

These little things are neat, but I can not figure out how they work. They come in a tiny, tiny package and expand a lot. I bought these to go into my aquavase and they just float around on the bottom. You cant stick any plants in them because they won't stay. They do not work in an aquarium, but they would be neat for some kind of aquatic plant. With the excess water taken off, they look cool and a plant would draw up the water that the crystal absorbed.

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