ALL 4 COLORS - This axolotl is one of those grow pets that slowly expand and grow after being submerged with water. Place the 2.25" x 1.75" egg in water and the creature will slowly grow up larger and hatch out of the egg into an axolotl. Full grown axolotl measures about 4" x 2" x 2". Dry out and use it again. It shrinks with salty water though most shrink simply from air after being removed from water. This is a fun bath or pool toy! Ages 6 . Box is 4.25" x 3" x 2.25". Please note that these eggs take at least 24 hours of being soaked in water for the egg to start to crack. Axolotl gets full size at about 48 hours. Expandable water toys or grow-in-water toys are made from a superabsorbent polymer. Superabsorbent polymers are long chains of molecules that soak up tremendous amounts of water because the water is drawn into and held by the molecules of the polymer. These polymers can absorb as much as 500 times their weight in plain water. They are toys that expand after putting them into water for several days.