Yet another cat story.
I used to have a contact juggling sphere. In my old apartment I would practice on summer afternoons and my cat would chase the reflections the crytal sphere made on the wall as I moved it.
In time I lost the ball and went on a multi year hiatus from the juggling hobby.
I recently decided to take it back up again, so I bought a new contact sphere (keep in mind, about five years have passed since I last used one - about a third of the average cats lifespan). I got home and took the ball out of its box and my cat saw me do this. It was a dull day and no light was reflected from the ball... but my cat took one look at the ball and went straight to the wall to wait for the reflection.
I found this fascinating. It not only clearly displayed long-term memory, but also she'd made a clear connection between the concept of the ball and the reflection it caused. Whoever said cats were dumb may, I think, not have actually owned one.