A century before cats dominated YouTube, they were the subject of one very adoring photographer.

Recently, a family member reached out to YouTuber Mathieu Stern with a fun fact: There was possibly a time capsule hidden in his old family home.

The photography experiment-focused video-maker looked into it, and sure enough discovered a box he estimates dates to roughly 1900, based on its contents — which included 120-year-old glass-plate negatives of cat photos.

“I then decided to develop them using one of the oldest ways to make solar prints: cyanotype,” he writes in a blog post.

Cyanotype is a photographic printing process dating to the 19th century that produces cyan blue-tinted photos, also called blueprints.

In the video, Stern is successful in applying the process, and he makes two blueprints of the ancient cats.

“She wanted her beloved cat not to be forgotten,” he writes in a video slide, cutting to a framed picture of the kitty.

He then develops the second glass plate, this one featuring two cats and a dog, before showing himself closing the time capsule back up.