This spiny mammal lays eggs, has no nipples, and sweats milk through its skin
Echidnas are one of only two kinds of mammal that lay eggs instead of giving birth — the other being the platypus. A female incubates a single leathery egg in a temporary pouch; the hatchling, called a puggle, then laps up milk that oozes directly through patches of its mother's skin, since echidnas have no nipples at all. Despite looking like a spiky anteater, they're more closely related to you than to any reptile.