A hair-like structure covering the flagella found in some algae (heterokonts and cryptophytes). It is approximately 15 nm in diameter, and usually consist of a tubular shaft that itself terminates in smaller hairs. It is composed of glycoproteins and, likely, carbohydrates. Mastigonemes may assist in locomotion by increasing the surface area of a flagellum. [ http://www.ncbi.nlm.nih.gov/pubmed/943397 http://en.wikipedia.org/wiki/Mastigoneme ]