Job 41:30 in the World English Bible
His undersides are like sharp potsherds, leaving a trail in the mud like a threshing sledge.
Context
29 Darts are counted as stubble: he laugheth at the shaking of a spear.
30 Sharp stones are under him: he spreadeth sharp pointed things upon the mire.
31 He maketh the deep to boil like a pot: he maketh the sea like a pot of ointment.