Just add water and watch the Water Marbles grow in size! The Water Marbles come in a variety of colours and once grown, you can keep your Water Marbles in an airtight container for weeks or they can be rehydrated once they are dehydrated! Water Marbles are biodegradable and each bottle contains approximately 13g of Water Marbles. All Water Marbles are packed right here in Australia. Please note that this contains small parts and therefore, should be kept out of the reach of children under 4. Please supervise use at all times.