Pill millipedes protect themselves from predators by rolling their jointed skeletons into a ball.

Edit Hook

References

"The pill millipede has the same strategy: its hard outer skeleton is jointed so it can roll into an impregnable ball, enclosing its head and numerous legs in armour plating. Not only is there no easy way in for the predator, but it would also need a much larger mouth to swallow a rolled-up millipede than a long thin stretched-out one." (Foy and Oxford Scientific Films 1982:21)

Book
The grand design: Form and colour in animalsBLA Publishing Limited for J.M.Dent & Sons Ltd, Aldine House, LondonJune 23, 1983
Sally Foy

Edit References

Living System/s