Origin of frustule
Examples from the Web for frustule
Frustule quadrangular, elevated at the angles into subconical processes oblique to the longitudinal axis.
Frustule membranaceous, elliptical, truncate, with broad ends.
Frustule membranaceous, constricted in the middle, with well-marked folds extending from the junction line in both directions.
Frustule broad, with rounded angles; septa curved; valve ovate, inferior apex produced.
Frustule of two saddle-shaped valves at right angles to each other.