When Orbeez dry, they shrink and become hard. When they are hydrated, they swell up to around 100 times their original size! As the water evaporates from them, or if they’re exposed to heat or sunlight for too long, the water is taken away and the beads begin to shrink back down in size. This process can take several days depending on how much moisture is left inside the tiny balls of plastic. Because of this dehydration process, it’s important not to leave your Orbeez out in a warm environment for extended periods of time as you risk losing them forever! When completely dried out over a few days, these fun little toys will be nothing more than small pellets that no longer grow when exposed to liquids.