Its tongue is always hanging out, as it sits on the sea floor. Shellder swims facing backward by opening and closing its two-piece shell. When Shellder sleeps it uses its broad tongue to burrow a hole in the sand and then sleeps in it. While Shellder is sleeping, it closes its shell, but leaves its tongue hanging out. Attaching to a Slowpoke and evolving into either Slowbro or Slowkin causes the Shellder to become parasitic, using the Slowbro or Slowking as a host. It feeds on Slowbro's sap secretions, which taste so sweet it refuses to let go. It will also feed off Slowbro's leftovers. Shellder are apparently attracted to the King's Rock since it is this item that makes the Shellder bite Slowpoke on the head and transform it into a Slowking. Slowking's yawn provokes it to release more toxins, thus causing the Slowking host to become more intelligent. Shellder evolves into Cloyster with the use of a Water Stone. Shellder will very likely spawn on islands in an ocean biome.