I created this little amoeba-jelly fish last year. I have it hanging in my bedroom since it's calming to look at. There's actually a lot more negative space in the original, but I had to crop it to fit in the scanner.
A photogram is made without a camera. You place your objects directly on photo-sensitive paper and expose them to light. The paper is then run through a color processor to develop. The end result is a negative shadow with tones that depend on the the transparency of the objects used. In this case, I used paper collage cutouts, which is why such a range of colors came through.