Mammal - mammary glands - modified sweat-glands with which to secrete milk to suckle their young - knockers - a fulsome pair of funbags. Mammals usually don't lay eggs; but the ones that do are called monotremes(platypuses, echidnas...). Mammals usually have a placenta; the ones that don't are either marsupials or the afforementioned monotremes. Marsupials … Read more