Ludion jellyfish form

These little colorful jellyfish shaped toys are sure to amuse children and adults alike. Dipped in a flexible transparent bottle filled with water, it is then enough to press the bottle to make the jellyfish go down and to release the pressure to on the contrary make it go up. A fun way to question density! Technical characteristics : - Size: Ø20 x 25mm - Color: blue, red or white (randomly depending on availability in stock) Explanations of the physical phenomenon: The ludion is pierced from top to bottom thus forming a column of air. Once the diver is immersed in water, the air remains trapped in the column. When the bottle is squeezed, the air compresses and the water enters the diver, thus increasing its density. When the density becomes greater than that of water, the diver sinks. When the pressure on the bottle is released, the air expands and the water is expelled from the central column, thus reducing the density of the diver. When the density of the ludion again becomes lower than that of the water, the ludion rises and floats.