Job 41:30

Sharp stones חדודי חרשׂ, chadudee chares, acumina testæ, vel testacea, sharp points of potsherds, are under him He can repose himself on rocks, or stones, whose edges, or points, are sharp, like those of shells, or broken potsherds; and yet he is not sensible of them, says R. Levi. and Ab. Ezra. His skin is so hard and impenetrable that they make no impression upon him, but are as easy to him as a bed of clay. He spreadeth sharp pointed things: &c. Hebrew, חרוצ, charutz, acutum, any thing which cuts, or makes an incision. The word also means, and is rendered by Bochart, tribula, an instrument used in thrashing corn, a kind of sledge, furnished with sharp iron wheels, which was drawn over the straw by oxen, and at the same time thrashed out the corn, and cut the straw into small pieces, reducing it to chaff. Heath, therefore, translates the verse, His nether parts are like sharp potsherds: he dasheth himself on the mud like a thrashing-cart.