What is the longest living pet you have owned?

My current two dogs and cat are all 12 years old. It's not exactly long, but i'm hoping to have them around for many more years.

I have and have had a lot of pet rats, and sadly they don't live very long, most commonly around 2 years before they start developing tumours or get strokes and have to be put down. I had a rat who was over 3 years old when she had to be put down - that's very impressive for pet rats nowadays! So based on how long an animal lives, it must have been that rat.