These animals show exceptional longevity with a highest reported age, for Ming the clam, of 507 years. This makes it the longest living non-colonial metazoan species with an authenticated lifespan.[4] [5] [6] It is unknown how long it could have lived if it had not been collected alive by an expedition in 2006. In 1868 one specimen, collected alive near Iceland, was 374 years old. The study of its growth rate and the oxygen isotope data showed that it had a highly variable growth at the peak of the Little Ice Age around 1550–1620 and mild climate near its end around 1765–1780 and had recorded the volcanic eruption of Mount Tambora in 1815.[7] One study found that in animals aged 4–192 years, antioxidant enzymes declined rapidly in the first 25 years, which includes the growth and sexual maturity stages, but afterwards remained stable for over 150 years. Though more detailed studies are warranted, it appears this species is a case of negligible senescence.[8]