Monkeys and apes manipulating their food is one of the most fascinating things to watch. How anyone could rinse a piece of fruit in their sink and not instantly recognize, let alone revere, our evolutionary heritage... I feel closer to these "beasts" than a, sadly large, portion of my own species at times like this.
The Bronx Zoo sure puts a lot of fruit in their enrichment jello. Our mandrills get jello with maybe just a few scattered raisins. And no red jello allowed. Visitors get very upset when they see red drops on the ground.
Note that you can't just follow the standard recipe, you have to use the recipe for jello jigglers, i.e., less water so the jello can be picked up.
Ah, I miss the "I am away from my computer" t-shirt. I loved that. :)
Raccoons (maybe just those from non snow areas) and ice cubes are similar fun. They can tell the stuff is water, but they can't figure out why it's not liquid. And their paws are just manipulative enough for them to grasp the cube and examine it in detail.