A disco ball. For penguins. Seriously. The penguins would chase spots of light, so the disco ball was a world of excitement for them. More evidence for the theory of cat/penguin duality.
There’s a penguin running around her feet, out of shot. On the right is a CD the keeper was holding, using it to reflect sunbeams down to the ground for the penguin to chase. Penguins like sunbeams, Charlie likes penguins.