I put a drinking glass into a small water-filled aquarium. Then, with a syringe, I let some drops of light blue ink fall into the water, right above the drinking glass. It diffused slowly, creating all these delicate shapes. It gave me a hard time to take some photos in the right time and angles, because, as usual, I had not prepared the tripod and everything thoroughly... and I didn't have enough light, so there's too much noise in the picture.