The rigid outer covering a plant cell is known as the cell wall. The cell wall is composed mainly of cellulose.
The sclera is tough and rigid because it is primarily composed of collagen fibers, which provide structural support and protection to the eyeball. This toughness helps maintain the shape of the eye and protects the delicate structures within it.
Protects the nucleus with a rigid layer of cellulose
The outer covering of euglenas is called a pellicle. It is a flexible layer made up of protein strips called pelliculin. The pellicle helps euglenas maintain their shape and structure while allowing them to move and change shape.
Corn has a tough outer layer called the hull that your body can't fully digest. This hull protects the inside of the corn kernel as it travels through your digestive system, so it remains intact when you eliminate it.
The stratum corneum is the tough outer layer of the skin.
The tough outer covering of bone is called the periosteum. It is a dense connective tissue that protects the bone and plays a role in bone growth and repair.
I think it is the cell wall or the cell membrane
The outer-most layer of a plant cell is the cell wall. This is mainly composed of cellulose, hemicellulose and pectin. The cell wall is a rigid structure that plays an important role in support, and is not found in animal cells.
Periosteum is a membrane that lines the outer surface of all bones,[1] except at the joints of long bones.
Exoskeleton/ Chitin
Cell Wall
This is called bark.
A porpoise has tough leather like skin body covering, that protects them from some predators.
A cuticle is part of the human fingernail. Cuticle can be used to refer to the organic hard outer covering of any organism, including arthropods (of which cricket is a member).
Schlera
The sclera is tough and rigid because it is primarily composed of collagen fibers, which provide structural support and protection to the eyeball. This toughness helps maintain the shape of the eye and protects the delicate structures within it.
It is a shell, as in a cockle shell or oyster shell.