It is called the exosketon. It is made from a hard protein, chitin, which arthropods often biomineralize for further strength.
Chitin
Exoskeleton/ Chitin
The external covering on arthropods is called the exoskeleton (or cuticle). It is made of a tough protein called chitin, a long chain polymer comparable to cellulose. Because it's inflexible, arthropods need to shed it (moult) in order to grow.
An arthroderm is an external covering of an arthropod.
what is seahorse outer-covering
The outer covering of the grain is called Husk.
Amphibians do not have outer covering.
an ant's outer covering is their exoskeleton
The outer covering of the eyeball is cornea.
Bat is a mammal, so it's outer covering is hair whereas bird's outer covering is feather.
Camels have hair as their outer covering.
Tonoplast is the outer covering of vacuole