MEGA BLOKS Sensory Toys for Toddlers, Move 'n Groove Caterpillar with Building Blocks and Pull String for Movement for Ages 1-3. Little builders will move and groove alongside this adorable caterpillar train. Toddlers can build a caterpillar train with motion and chain blocks, and a pull string in the front to get it rolling. Then, they can add a ladybug with a pop block, snail with a turn and click feature, and a butterfly with textured wings on the caterpillar’s back to come along for the ride. Toddlers can also discover a mirror flower, textured antennas, and a bee bead block.