These are upside-down jellies, also called upside-down jellyfish. Unlike most jellyfish, the upside-down jelly sits at the bottom of the water with its bell down and its tentacles up. In the picture above, you can see that some of the tentacles are green. These tentacles have algae growing on them. The algae and the jellyfish have a symbiotic relationship, which means that they help each other. The algae attracts animals that eat algae, and then the jellyfish eats those animals before they eat the algae.
Do these look like giant raindrops about to fall? It is actually the bell of an upside-down jellyfish. At the exhibit, they had a tank of upside-down jellies above our heads so that we could see the bell.
Crabs sometimes crawl under an upside-down jellyfish and pick it up. It does this for protection.
We have a short movie of the upside-down jellyfish, but it is not ready just yet. Check back soon to see it!