While we know plants ( like trees, moss like plants) are the longest living plants ( and maybe some alien humanoid species out there ) the known world's oldest creature is revealed to be 507-year-old shellfish called Ming – until scientists KILLED it by opening it up to check its age.
Kinda interesting read.
http://www.dailymail.co.uk/sciencete...shellfish.html
Wonder how long our maxima clams live.