In 1964 Jack Barnes confirmed the cause of the syndrome was a sting from a small box jellyfish: the Irukandji jellyfish, which can fire venom-filled stingers out of its body and into passing victims. To prove that the jellyfish was the cause of the syndrome, he captured one and deliberately stung himself while his son Nick and a local lifeguard then observed the resulting symptoms (before rushing him to the ICU).[2][23][24] Other cubozoans possibly can cause Irukandji syndrome;[10] those positively identified include Carukia barnesi, Alatina cf. mordens, Alatina alata, Malo maximus, Malo kingi, Carybdea xaymacana, Keesingia gigas, an as-yet unnamed "fire jelly", and another unnamed species.[4][25][26]