Pellicle

Noun

1. A thin skin or film.
2. A cuticle, the hard protective outer layer of certain life forms.
3. The outermost layer of a mushroom; the skin of a mushroom cap; especially, a surface that is viscid and easily peels off.
4. A thin layer supporting the cell membrane in various protozoa.<!--[[w:pellicle (biology)]]-->
5. The growth on the surface of a liquid culture.