Nearly all of my stuff is/was long-lived. My first fish was a wild caught female ocellaris clownfish. She was an adult when I bought her and I had her for a little over 12 years. The current male-now-female is 8 years old. I have had some wrasses also last for 10 years. Some inverts (other than corals) are nearing the 10 year mark for me, notably a serpent starfish. The oldest things are my anemone (14 years in captivity), my brain coral (12 years) and bubble coral (11 years).
If well taken care of, many of these animals can live a very long time.
Edit: While I do try to take care of things, I need to add that a lot of these things have shocked me with how long they have lived in my care. They have endured tough times before--some of them withstanding some BAD mistakes as a newb. If anything, I tend to attribute my success more to their raw tenacity than for any other reason. That is why I am convinced that once something is settled, it can be nearly bulletproof (with exceptions).