They trod noiselessly upon a stair carpet that its own loom would have forsworn. It seemed to have become vegetable; to have degenerated in that rank, sunless air to lush lichen or spreading moss that grew in patches to the staircase and was viscid under the foot like organic matter.
Source: wiktionary
The pool’s bottoms and sides were lined with a blanket of viscid slime, and the three statues in the middle, the three Sirens of Titan, were under a mucilaginous hump.