Unibō (ウニボー), from "uni" or "sea urchin", are spiky round enemies that inhabit flying and swimming areas. Unibō are nearly indestructible; in Super Mario Land 2: 6 Golden Coins, they can be defeated by only a Star or Koopa Shell. They remain stationary until Mario comes near, at which point they will shake on the spot to make themselves harder to avoid. They reappear in Mario & Wario, slightly redesigned to look more like Urchins and their visible eyes removed (although they could be facing away from the screen). In addition, they now come in two varieties: those with blue bodies move vertically, and those with yellow bodies move horizontally. In addition, they no longer sleep and are contantly moving around.