Jellyfish
While our Moonjellies are generally harmless to humans, they can sting but our skin is generally too thick to penetrate, the most venomous creature in the sea is one of their cousins: the Sea Wasp. The Sea Wasp is a species of box jelly that is found near Australia. One box jelly is believed to carry enough toxin in its body to kill up to 60 grown men!
Jellyfish