A range of jelly-like species are called box jellies. The name derives from the 4 distinct sides to the animal that give it a box like appearance. The larger species can inflict a sting that will severely injure or cause death.
The box jelly is clear or pale blue in colour making them extremely difficult to see in the water. In Northern Australia many swimming areas are closed during box jelly season.
Box jellies are not true jellyfish.