The Baby Einstein ocean explorers opus's stack & stream sensory stacking cups help baby engage in multi-sensory play with 4 large nesting cups and a clamshell water squirter to help baby stack, pour and discover colors, textures, and more.   Features:   Opus the octopus cup changes color in warm water. Other cups feature vibrant colors to support color learning and visual stimulation, as well as textures for multi-sensorial exploration. Helps build cause and effect, fine motor skills, and sensory learning as baby stacks, pours, sits, and nests cups. Great for water play, as slotted cups allow baby to stream water.