They come in various sealife and dinosaur themed. Squeeze the liquid filled tube and it will slide up or down in your hand, making it quite a slippery fascination for your fingers. Fun game for rainy days or car journeys or to play with friends. Also a good calming tool due to its repetitive motion.
It will also increase gross motor skills as well as hands and arm muscles which will be good for injury recovery therapy. The feeling of the water flowing through the plastic is a pleasant sensory experience as well, proving useful for anybody with autism or seeking sensory input.