Shellder is a black pearl-like Pokémon encased within a spiky, blue-violet bivalve shell. It has two round white eyes with tiny black pupils. It has an enormously long red tongue, which it uses to burrow itself into sand and to lure and capture prey. Its body is known to be soft and tender; however, its shell is said to be harder than diamond. It swims around its sea floor home by rapidly opening and closing its shell while facing backward.