Oldest battery ever?

Yesterday I decided it was time to turn on my steam heat for the season and noticed the display on my Lux 500 thermostat was blank. I've been in the house since 2002 and am embarrassed to admit never even realized it had batteries despite having worked on virtually every other part of the heating system. It turns out they have been expired for 23 years and finally died. I am so absolutely astonished they did not leak that I had to share it with you all. I put in disposable lithium batteries which don't expire until 2050 so I guess I can forget about it for a while again.