pellicle

/ˈpɛlɪkəl/
noun
  1. A thin skin or film, especially on a liquid surface or on a living organism.
    • A pellicle formed on the surface of the milk as it cooled.
    • Some bacteria produce a protective pellicle around their cells.
    • The pond was covered with a green pellicle of algae.
  2. A thin membrane or cuticle on a plant or animal, such as the skin of a fruit or the outer layer of a protozoan.
    • The pellicle of the grape gives it a slightly waxy feel.
    • The insect's pellicle helps prevent water loss.
    • Under the microscope, the pellicle of the paramecium is clearly visible.