I found this beauty while snorkeling in Carriacou, Caribbean. The bottom of the lagoon was carpeted with them.
Cassiopea xamachana is a jellyfish that is found in Bermuda, throughout the Caribbean Sea, and some areas of the warm western Atlantic Ocean The common name of this species is the upside-down jellyfish. Given its life style, it does not look like the typical jellyfish, appearing as a greenish gray-blue flower on the seafloor. It is found on the muddy bottoms of inshore bays and ponds. Because they live their lives on the bottom with large portions of their carbon and nutrition coming from their symbiotic zooxanthellae, they tend to be in shallow areas saturated with sunlight. This species reproduces through strobilation, similar to most other jellies, but with varying seasonality. As with other cnidarians, C. xamachana has nematocysts covering its tentacles and digestive tract. It uses these stinging cells for both feeding and defense .