The reef stonefish is dangerous because its sting causes intense pain that can actually be strong enough to kill a person. In this case, death is brought about as a result of the shock caused by the extreme pain that accompanies a stonefish's sting.
Stonefish stings are painful due to the venom contained within their spikes; the pain brought about as a result of these stings is usually not improved by painkillers such as morphine. The fish gets its name for its advanced physical camouflage, which allows it to blend in with its rocky ocean surroundings. The stinging spines on its back are sharp enough to penetrate rubber shoe soles.