Pygmy hippopotamuses (Hexaprotodon liberiensis) 'Thug', right, and 'Nicky' line up to have their teeth cleaned with a new giant toothbrush at the London Zoo earlier today. The hippos' teeth are regularly cleaned by zoo keepers as part of their care routine and until now a broom for each hippo has done the job perfectly. You write the cutline. (AP Photo)

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