Elongate, soft, vermiform animal body with two reduced shell valves at the anterior end of the body. These are the cutting and boring instruments to reduced wood to dust particles by rasping action. Distal end of the pallets with a warty, bladder-like calcareous extension and widely fused siphons. In adults, dorsal portion of the anterior slope with the disc and the eroded posterior lobe; the auricles internally form a shelf where the disc overlaps. Apophysis finger-like, arising from the shelf at the junction of lobe and disc. Colour: exterior light grey to whitish, interior white.