Wild Things: The Most Extreme Creatures | LiveScience: "Toxitolerant organisms can withstand high levels of damaging agents. They can be found swimming around in benzene saturated water or in the core of a nuclear reactor.
One species of bacteria, Deinococcus radiodurans, can withstand a 15,000 gray dose of radiation - 10 grays would kill a human and it takes over 1,000 grays to kill a cockroach."
