They slip, slide and bounce! Water marbles grow up to 200 times their size when placed in water! Watch them grow, then watch them slip, slide and bounce! Fun to squish and play with for hours. Let them dry, and they return to their previous size. Can be used again and again. Experiment with different amounts of water to make different sized marbles. Package includes 5 grams of water marbles in assorted colors. Nontoxic and not meant for children aged 4 and younger.