As a young boy in the 1970s, I was excited to receive my first set of “Grow Monsters.” Cheap toys made from a super-absorbent polymer, these small, shapeless specks would expand by up to 500% of their original size when placed in water. Fullgrown, they were supposed to resemble dinosaurs and other fearsome creatures, with the process designed to delight and amaze naïve young lads like me.