The stupidest mammal has to be the ai because he needs three to do what the unau manages with only two. And that's not a lot.

Hippopotamus? We're not back with Flanders and Swann again are we?

Hippopotamus? Reminds me of my favourite cartoon. Shows two hippos nostril deep in a jungle pool, just floating idly. One says, "You know, I keep thinking its Thursday."