hippopotamus, hippo, river horse, Hippopotamus amphibius
['box turtle, box tortoise', 'axolotl, mud puppy, Ambystoma mexicanum', 'wallaby, brush kangaroo', 'flatworm, platyhelminth', 'sunscreen, sunblock, sun blocker', 'chambered nautilus, pearly nautilus, nautilus', 'Gila monster, Heloderma suspectum']