Fibrous interior of the dishcloth gourd used as a bath sponge (6)
I believe the answer is:
loofah
(Other definitions for loofah that I've seen before include "Washing aid" , "Dried part of plant used as a bath sponge" , "Bath-time scrubber" , "Dried gourd pod used as bath sponge" , "Hard bathroom sponge" .)