This is one of the most dangerous animals in the sea, Its lethal sting is caused by microscopic cells (nematocysts) which reside in the trailing tentacles, Contact causes excruciating pain and may result in the death of human victims, Fortunately, this jellyfish is seldom encountered on coral reefs, as it prefers a coastal habitat, Extreme caution must be exercise when wading or swimming in these areas. The best way to prevent being stung is to completely cover up with a rubber wet suit, although a lycra suit or body stocking can also prevent serious injury, Australia seems to be the worst-affected area, having recorded a number of fatalities, often children, The animals congregate near shore during the summer wet season, when warning signs are posted at popular beaches to discourage swimming The Box Jellyfish sometimes grows to 45 cm (18in),but even small jellies are dangerous. The semi-transparent, square body, with clusters of tantacles dangling from each lower corner, is difficult to detect.