I got to spend a day with the tuatara in the 'Museum of the Southlands' in Invercargill (which the locals call 'Inver-gumboot') NZ. I was on independent motorcycle tour, spent the day there as I was a bit under the weather. The keepers there were unclear as to how long a tuatara might live in captivity as the oldest ones were still alive — and the only part known about their age when captured was that they were ‘not juveniles’. This was a few decades back.

I was pretty stationary (under the weather) and after watching them a few hours came to the conclusion that their secret to longevity was not moving at all for hours on end. Come out of a burrow in the AM, then hold very still - unless a shadow passes overhead. The museum got the local airport flight paths changed so this wouldn't happen on a daily basis.

They are indeed cool little beasties. I was lucky enough that the day I was there one of their eggs hatched open (preceded by a sudden mob of schoolkids - it wasn't unexpected).

Anyway, the lessons I took away were 1) be an ectotherm and 2) don't move once you're out of your burrow. :-)