"Negligible senescence"

I failed a Gullibility Test over at the Museum of Hoaxes this morning...one of the stumpers was related to Turtles...the question (# 5) was simply: Do turtles die of old age? The answer is, no, they do not! Their feedback to my mistaken answer included the following insights, which I have fact-checked with my biologist office mate (and he has a PhD!).

Turtles exhibit what is known as 'negligible senescence.' In other words, unlike humans, they do not continue to age once their bodies reach maturity. (This, compared to many people, who reach maturity in their bodies, though their brains never do.) In theory, they might be able to live forever, though in practice this would never happen. Injury, predation, or disease eventually kill them. But turtles have been known to live beyond 150 years without exhibiting any signs of old age. Fish and amphibians also share this enviable characteristic.

I've been around nearly 1/2 a decade, and yet I've never known of this...that's what I get for nodding off in Biology. It reminds me of all the fantasy novels I've read, where some wizard or crone is 100's of years old--not so fanciful anymore, eh? I wonder if scientists have been trying to figure out a way to isolate/capture this trait, so that we might live longer/better lives? Surely so. I wonder if, as a side effect, one would smell fishy? Would it be worth it--to stink, be covered in scales, live in muck--if it meant 'eternal life' or at least a longer life? I've always shunned the healthy lifestyle crowd, since I've always been under the assumption that even the cleanest livin' can't twart old age.

If we can figure out what makes the turtle tick, however...