It is the anatomical part of some animals that do not have an internal skeleton to give the animal solidity (like the bones in mammals do). An exoskeleton can be in the form of a tough inflexible...
endo I believe
Endoskeletons
Exo means outside. So an exoskeleton is just a skeleton that's outside the body, rather than inside.
Arthropods such as: Scorpians Spiders Crabs Lobsters Centipedes Millipedes Shrimp Insects Crayfish