The Big Tongue Clam shares a similar anatomy with clams: its interior is encased in a sharp, hard shell, with two pointed spines on each of the upper and lower valves, yet its insides are surprisingly soft. Its eyes are nestled within the black, fleshy tissue inside the shell, and its large tongue is perpetually exposed, no matter the time of day.

Taxonomically, the Big Tongue Clam is related to shell-less sea slugs and sea slug-like Pokémon. It skillfully uses its constantly protruding tongue to dig through seabed sand in search of food. At night, it burrows into the sand with its big tongue and sleeps there. Although it keeps its shell tightly closed while sleeping, its tongue remains extended outward. By repeatedly opening and closing its two shells, it propels itself backward at a fairly rapid pace. Sand particles trapped inside the shell, mixed with the clam’s bodily fluids, can form beautiful pearls; however, these are often expelled because they get in the way, and their value is said to be less than one-tenth that of pearls from pearl oysters. Even when the shell is shut tight, the Big Tongue Clam’s tongue always sticks out. If you try to forcibly pull the tongue, the clam will panic and open its shell. Once the shell is open, the soft interior becomes highly vulnerable if attacked. When it strikes with its shells, the tender inner parts are exposed, making this a desperate, all-or-nothing attack. Encased in a shell harder than diamond, which can deflect any attack, it nonetheless struggles against spiky ammonites, fluffy eaglets, and toothy color-skinned fish. In the past, people collected its shells to craft shields. When a Slowpoke ventures into the sea to hunt, if a Big Tongue Clam bites its tail, it turns into a Slow Shell; if it bites its brain, it becomes a Slow King. It is said that the Big Tongue Clam clinging to a Slowpoke’s tail survives by feeding on the leftovers the Slowpoke leaves behind.