Sis forSponge

A modern day sponge is made from a kind of plastic that has been filled with bubbles while it is still liquid. The result is that sponges are soft and full of small holes. Sponges are great for cleaning things with, and because of the holes they are very good at soaking up spilled liquids. Before modern sponges were invented, people used to use sea sponge skeletons as cleaning sponges.