The mantle is a layer inside a planetary bodybounded below by a core and above by a crust. Mantles are either made of rock or ices, and are generally the largest and most massive layer of the planetary body. Mantles are characteristic of planetary bodies that have undergone differentiation by density. The mantle is bounded on the bottom by the planetary core and on top by the crust. In addition to the Earth, the other terrestrial planets, a number of asteroids, and moonshave mantles.