Pill bugs (also called roly polys) are famous for their ability to roll into a tight ball when threatened-- an ability exploited by many curious children. This process is known as conglobation or volvation; it鈥檚 also been observed in armadillos, earthworms, pangolins, hedgehogs, millipedes, and snakes.
(Image: A pillbug, (Armadillidium vulgare) rolled into a defensive ball by James Castner)
If you like what I do, consider leaving a tip or buying me a ko-fi!