False-colour scanning electron micrograph (SEM) of filiform papillae on the surface of the tongue. Filiform papillae, also known as conical papillae, are covered by epithelial cells apart from their white tips which are formed by the fibrous protein keratin in order to increase the papillae's strength. Filiform papillae have mechanical and tactile functions. They form a rough surface which helps the mastication process. Each papilla contains nerve endings which transmit tactile information to the brain. At centre a papilla is partly covered by green coloured bacteria. Magnification: x335 at 6x7cm size.