A gastric shield is an organ in the digestive tract of bivalves, tusk shells, and some gastropods against which a crystalline style typically rotates, in an action resembling that of a mortar and pestle. The gastric shield is permeated by microcanals which transmit digestive enzymes from the stomach, and serves to protect the cells of the stomach lining from the abrasive effects of the style.^[1]

References

^ Saleuddin, A. S.M.; Wilbur, Karl M. (1983). The Mollusca: Physiology, Part 2. Academic. p. 95. ISBN 9780323139212.

v t e Bivalve anatomy
Shell	Callus Hinge line Hinge teeth Ligament Lira Lunule Nacre Pallial line Pallial sinus Periostracum Prodissoconch Resilifer Resilium Sculpture Umbo Valve Beak Annuli
Other hard parts	Byssus Pearl Sea silk
Soft parts	Adductor muscles Ctenidium Gastric shield Mantle Nephridium Siphon
Other	Abductin Glochidium Pseudofeces Trochophore Veliger

v t e Gastropod anatomy
Shell	Aperture Apex Body whorl Callus Columella Lip Lira Nacre Periostracum Peristome Planispiral Plait Protoconch Sculpture Selenizone Siphonal canal Siphonal notch Spire Stromboid notch Suture Umbilicus Valve Varix Whorl
Other hard parts	Clausilium Love dart Operculum Pearl Radula
External soft parts	Caryophyllidia Caudal mucous pit Cerata Cnidosac Mantle Mentum Notum Parapodium Pneumostome Rhinophore Semper's organ Siphon Suprapedal gland
Internal soft parts	Circulatory system of gastropods Crop Ctenidium Digestive system of gastropods Diverticula Excretory system of gastropods Gastric shield Hancock's organ Hepatopancreas Hypobranchial gland Nephridium Nervous system of gastropods Nidamental gland Odontophore Oesophageal pouch Osphradium Reproductive system of gastropods Respiratory system of gastropods Sensory organs of gastropods
Other	Epiphragm Pseudofeces Torsion Circumesophageal nerve ring Trochophore Tyrian purple Veliger