Claim: There are several venomous species of jellyfish in Australia, including the Irukandji, which have killed three people in the 21st century.
Evidence: In fact, no evidence exists to suggest that any of the five victims displayed two universal features of Irukandji syndrome: delayed onset (5-40 min to illness and 2-12 hrs to death) and highly visible distress (vomiting, difficulty breathing, extreme pain, etc). When properly treated, a single sting is normally not fatal, but two people in Australia are believed to have died from Irukandji stings in 2002 during a rash of incidents on Australia's northern coast attributed to these jellyfish—greatly increasing public awareness of Irukandji syndrome. 
When properly treated, a single sting is almost never fatal; however, two people in Australia are believed to have died from Irukandji stings, which has greatly increased public awareness of Irukandji syndrome.