[reasonattlm]

Lobsters are probably on the way out of the possibly immortal and into the negligibly senescent category. They were only in the former category because there was no way to measure the age of an arbitrary sample of lobsters retrieved from the wild. Researchers did find a way to measure lobster age reliably a few years back, so data will emerge on their life spans over the next few decades. It isn't a well populated or well funded area of study, so results tend to lag.

http://www.sciencemag.org/news/2012/12/tree-rings-lobsters