In October of 2007, a research ship off the coast of Iceland dredged specimens off the sea-floor. One of these specimens was an Arctica islandica clam. Scientists were able to estimate the age of this clam by counting it’s rings (similar to counting the age of a tree) and found it to be 405 years old!
When it’s life first began Shakespeare was writing Hamlet and Twelfth Night. Mid-way through it’s lifespan Thomas Jefferson was elected to presidency.
However, by bringing it up from the sea they inadvertently killed it, so no one is sure how much longer it could have lived.