In the waters of northern Australia lurks the Irukandji. This small jellyfish approximately 2.5cm in diameter has a string that can kill a human in a matter of days!
Not much is known about the Irukandji as it is very fragile and cannot live easily in captivity as even bumping into a aquarium wall or fish tank wall will generally kill the Irukandji.
It is known however that the Irukandji has stingers not just on its tentacles but also on its brow, these stingers have a single point to sting with similar to that of a wasp.
The venom of the Irukandji has no known cure once into the body. The symptoms are especially nasty, usually appearing within 30mins of the sting such as; muscle cramps, burning skin sensation, vomiting, and excrutiating pain to internal organs.