Exoskeleton

Spiders, for example, or lobsters, have tough outer shell systems which provide rigidity and shape to their bodies.

Medieval armour (in the case of mounted knights) furnishes an example of an artificial human exoskeleton. Modern motorists use automobiles as temporary protective exoskeletons in harsh traffic environments.

Science fiction authors perennially popularise the idea of personal powered exoskeletons[?].

Excellent as a principle of defence, exoskeletons may neverthess cause problems where entities carry an excessive weight to surface-area ratio; or whenever organism growth requires an enlarged exoskeleton.