300000000 age month third absolute alkali age
plutonium_238 has not half_life_of_86.4_years 3_old is not 3_through_4. plutonium_239 has not half_life_of_about_24,000_years plutonium_239 has not half_life_of_24,390_years plutonium_238 has half_life_of_86.4_years bronze_age is time_period. plutonium_239 has half_life_of_about_24,000_years plutonium_239 has half_life_of_24,390_years 3_old is 3_through_4. middle_age is time_of_life.