easywhat am-i

I shrink smaller every time I take a bath. What am I?
Common Wrong Answers
“Sponge”
A sponge absorbs water and expands when wet, rather than shrinking.
“Bubble bath”
Bubble bath refers to the product used for bathing, and it doesn't shrink; in fact, it creates bubbles.
“Towel”
A towel absorbs water but does not shrink in size; it might get heavier when wet but retains its dimensions.