Tegillarca granosa is a species of marine bivalve mollusk in the family Arcidae, commonly known as the blood cockle. It is widely distributed in the coastal waters of the Indo-Pacific region, including Southeast Asia, China, and parts of the Indian Ocean, where it inhabits muddy tidal flats and estuarine environments. The genus name Tegillarca combines Latin tegillum (“covering” or “small roof”) with arca (“chest” or “box”), referring to the box-like shell structure typical of ark clams, while the species epithet granosa derives from Latin granosus, meaning “granular” or “grainy,” describing the ribbed, textured surface of the shell.

This species has a thick, rounded shell with prominent radial ribs and a dark exterior, enclosing soft tissues rich in hemoglobin-like compounds that give the flesh its characteristic red coloration, hence the common name “blood cockle.” Unlike many bivalves that rely solely on dissolved oxygen in water, Tegillarca granosa contains hemoglobin in its blood, allowing it to tolerate low-oxygen environments such as muddy sediments. It feeds by filter feeding, drawing in water to extract plankton and organic particles, and plays an ecological role in nutrient cycling in coastal ecosystems.

As a food source, Tegillarca granosa is widely consumed across East and Southeast Asia. It is typically boiled, steamed, or lightly blanched and served in dishes such as noodle soups, stir-fries, and salads. In some culinary traditions, it is cooked briefly to retain a tender texture and distinctive flavor. The flesh is rich, slightly metallic in taste due to its iron content, and valued for both its flavor and nutritional properties.

Nutritionally, Tegillarca granosa is a good source of protein, iron, zinc, and vitamin B12. The presence of hemoglobin contributes to its high iron content, which is readily bioavailable. It also contains taurine and other amino acids common in marine shellfish. However, because it is often harvested from coastal and estuarine environments, there is a risk of contamination or pathogen accumulation if not properly handled and cooked, and thorough cooking is generally recommended for safety.