Water Marbles Tube

These colorful water marbles are polymer balls that absorb and expand 100 times their size in water. They're slippery, fun, and full of scientific possibilities! Great for starting seeds and growing plants so that the roots can be seen! They can also be used in a garden (to add moisture to soil) or at home (in a vase with flowers). They're non-toxic and biodegradable. Leave them out of water and they will slowly dehydrate back to their original size. Marbles come in a 5.5" plastic test tube, which holds about 1.8 fluid ounces.