Water beads are our new favorite sensory material these days! They are actually made for flower vases, but they are wonderful for sensory play because while they look like shiny marbles, they are soft, squishy and slippery to the touch. Plus they bounce on hard surfaces, and they disappear in water! We are totally fascinated by these things and have spent many, many hours exploring with them! You can order them online or find them at most craft stores. We bought ours at The Dollar Tree.