Longest living marine invertebrate

The tubeworm called Lamellibrachia which survives by digesting seeps of oil leaking from the sea floor, can live between 170 and 250 years.  A team from Pennsylvania State University marked groups of the tubeworms with a blue dye. A few years later the worms were recaptured and measured once again. The experiment showed that to grow to a length of 2 metres, a typical size, it takes between 170 and 250 years.