I've got a brittle starfish that is at least 14 years old. I say at least because he hasn't grown at all since I got him as a birthday present from my then little kids in 1998. It's been through tank crashes and moves and all sorts of my mistakes. Wonder how old they get in the wild?
I also have a sebae anemone (crispa) and a toadstool that's at least 11(just found a pic from 2001) and lived through three moves to three different tanks.
What's your oldest creature/fish?
I have then and now pics if you guys are interested.