Share 'Evolution of Steelpan Sticks/Mallets'

Hi everybody, I know lead sticks started out as just sticks without rubber and then people started wrapping bike tire tubing around the sticks. One of the things I don't know though, is how did sponge balls for bass pans come to be. Were those mallets ever wrapped rubber too? I have done some experimenting with wrapped rubber so I am curious as to how the sponge balls became the norm. Thanks! Matt