【Reading】まつぶ

【English Name】Whelk (Matsubu)

Matsubu, also written "ma-tsubu" (true whelk), is a large gastropod classified in the genus Neptunea of the family Buccinidae. It is positioned as the highest grade among tsubu shellfish, and is often served as sashimi or nigiri at sushi restaurants and traditional Japanese restaurants. It is a rare topping that hardly ever appears in ordinary supermarkets.

The shell grows to about 16 cm in height and about 10 cm in width, with developed growth lines visible on the spiral portion. The shell color varies among individuals from a reddish brown to a flesh tone. It inhabits the cold waters from Hokkaido and northward to the Bering Sea, dwelling on the seabed at depths of around 10–1,200 m.

The greatest appeal as a sushi topping is the distinctive crisp, crunchy bite and the rich sweetness that spreads the more one chews. The inherent flavor of the shellfish is abundant, and one can enjoy a pleasant, springy texture. In nigiri it is generally served sliced thinly, and it also pairs well with wasabi.

An important point of caution during preparation is that a toxin called tetramine is contained in the salivary glands, so they must always be removed when butchering. Until the 1990s it was an ingredient limited to Hokkaido, but it can now be enjoyed at sushi restaurants nationwide.