For me it's this holey blanket that was bought for me as a baby. It's still very comfy!

I wonder what it'll look like in another 40 years

This aluminum Water bottle. It has been with me for at least 25 years now. We traveled the world together several times over. It had to be rescued from lost&found boxes a bunch of times and I still use it every day.

I've been wearing this necklace for about 30 years