Job 41:30

30 Its undersides are jagged potsherds, leaving a trail in the mud like a threshing sledge.

Read Job 41:30 Using Other Translations

Sharp stones are under him: he spreadeth sharp pointed things upon the mire.
His underparts are like sharp potsherds; he spreads himself like a threshing sledge on the mire.
Its belly is covered with scales as sharp as glass. It plows up the ground as it drags through the mud.