I wanted a craft we could work on together so I got some supplies and let her do as much as possible.
I took four dessert sized paper plates and one square paper dinner plate. With the TLT's Crayola Washable paints, she and I plopped down on the tile on a plastic table cloth and painted the four small plates red and orange and the larger one blue.
Once all the pieces were dry, I cut small "x"s into the plates and strung them together with blue yarn to hang the small plates from the large one. I put the "jelly fish" at the low hanging ends of the green strips of tissue so it would like like they were swimming through seaweeds. As a final touch I cut a piece of bubble wrap into a blob-y shape with tentacles to look lie sea foam and put it on the top of the mobile with the sides hanging over.