Meaning
砂肝 (すなぎも, Sunagimo) is Gizzard, a Japanese food (viscera).
What is Gizzard?
Sunagimo means "gizzard". Chicken gizzards have a unique, crisp texture and a mild flavor. The sunagimo pictured here are flavored with salt. Gizzards are specialized stomachs constructed of thick muscular walls, and are used for grinding up food, often aided by particles of stone or grit.