Papillae on the tongue of a bat. Coloured scanning electron micrograph (SEM) of the tongue of an insectivorous bat, showing a dense arrangement of filiform (scale-like) papillae. Papillae are small projections on the tongue. Some house taste buds, but filiform papillae are purely mechanical, giving the tongue its rough surface. Filiform papillae are found on the upper, front surface of the tongue.