The Shaggy Ball
Bonnie bought the kids these on a recent trip to a store, and I think I'm getting more satisfaction out of them than they are.
The Shaggy Ball is a rubber ball that's covered with tendrils like a sea anemone. The material is colored but translucent, and she picked up pink, green and orange. It's partially inflated so you can squish it a bit, but the tendrils also feel very nice against the skin of your hand.
Bonnie bought them ostensibly because they have some therapeutic value -- clinicians have been using them for years for kids with sensory issues, so she thought it'd be nice for Robert to have, both as stress relief and as something to fidget with.
But what makes the Shaggy Ball particularly entertaining is that there's another, smaller ball inside of it that's sealed with lights and a watch battery inside of it. It's pressure sensitive, so when you hit the Shaggy Ball against the palm of your hand or another object, the lights activate and glow blue, red and yellow in a flashing sequence.
The net result is that you hold in your hand this unearthly-looking glowing thing that looks like it came straight off the set of an SF movie.
Oh, and there's a finger hook, so you can attach it to your hand and slap it around.
Heartily recommended.