What's the oldest living thing that isn't microscopic?
The oldest living non-microscopic things are certain Bristlecone Pine trees, which are found in California. Some of them are literally thousands of years old!
Bristlecones are actually not that big, and grow only a hundredth of an inch per year. Part of their evolutionary strategy for living so long is that they don't expend much energy on growth, saving it all for getting them through the long, frozen winters in the white mountains.
The oldest one we know of is called Old Methuselah. It's roughly 4,760 years old.