I think it's called the membrane? LOL!
Cell membrane
The thin outer covering of an animal cell is called the cell membrane. It is a semi-permeable membrane that controls the movement of substances in and out of the cell.
The thin outer covering of an animal cell is called the plasma membrane. It serves as a barrier that regulates the passage of substances in and out of the cell.
The outer covering of an Arowana are scales. They have a large amount of scales and some thin skin on their fins that fit the length of their long bodies.
Guard cells have a thin outer covering, called the cuticle, to allow for the efficient exchange of gases like carbon dioxide and oxygen during photosynthesis and respiration. This thin covering also helps guard cells to respond quickly to changes in environmental conditions, facilitating the opening and closing of stomata to regulate gas exchange.
the squids body is covered in a thin layer of sperm that helps it get away from its prey
the outer buttocks
The outer surface of the leaf has a thin transparent waxy covering called the cuticle
what is seahorse outer-covering
The thin, outer covering of the bone is tough, and provides a safe place for muscles to attach.
The outer covering of the eyeball is cornea.
Amphibians do not have outer covering.