The box jellyfish is shaped like a box with 4 distinct sides, each about 20 centimeters long. Box jellyfish have about 60 3-meter-long tentacles, each covered with stinging cells that store venom, and are often also called sea wasps. They live mainly in the coastal waters of northeastern Australia, for example, often floating in shallow waters off the Queensland coast.

There is a species of Australian box jellyfish that is considered to be the most toxic jellyfish known in the world to humans. Its poison is so strong that it can kill a person in less than three minutes. They are active from November to March each year. The box jellyfish is translucent in the water, making it difficult to detect. Moreover, this jellyfish has dozens of tentacles that can be up to three meters long and about five thousand stinging cells, which can pierce the victim's skin and release venom. An adult box jellyfish has billions of venom sacs and needles all over its tentacles, enough to kill up to 20 people, and if you get stung by them, you'll die of respiratory distress within 30 minutes. However, scientists have discovered that the box jellyfish is afraid of the color red, and at the sight of red it will immediately turn around and quickly swim away in the opposite direction. So you can use red objects to prevent being stung by them secretly, such as pulling on the red protective net, wearing a red swimsuit and so on.