Armadil

It spends the killing heat underground in tunnels it maintains with an obsessive's care, emerging in the cool to root for tubers and the fat grubs that live among them. Its digging reshapes the ground it lives in, aerating soil and, incidentally, providing homes for a dozen smaller creatures that move into its abandoned galleries. Threatened above ground it still balls up, but a grown Armadil balled up is a boulder, and predators that once tried their luck on the smaller form learn to walk on by.