noun
Japanese egg cockle; Fulvia mutica
A species of edible saltwater clam found in Japan, often used in sushi and sashimi.
鳥貝は寿司ネタとして人気がある。
The Japanese egg cockle is popular as a sushi topping.
The name 鳥貝 (literally 'bird shell') likely comes from the shape of the shell resembling a bird in flight, but the exact origin is uncertain.