Environmentally Material – Made of non-toxic environmental friendly resin and not easy to break or fade. Circular particles with high elasticity and good toughness. Good Water Absorption – Need only 3-4 hours in water to expand. Will shrink if being wrapped by tissue and expand again in water. Funny to play with.
https://www.amazon.com/UMIKU-Rainbow-Growing-Tactile-Sensory/dp/B075FRZ53W