Film

Yes!
… I have found some batteries for my Pentax SLR.

I found it with a 36 photo Kodak Ektar 100 film inside 8 exposures taken many years ago. The film has a 2017 expiry date so it is likely they were taken many years before probably 2012/13.

I have taken 21 rather random shots so far so 10 or less to go.