These were little animals - usually octopus-like - crafted of soft, soft rubber. They were tacky (not like kitsch but like sticky... well maybe they are a little kitschy...) so they would sort of stick to smooth surfaces like windows and walls. As gravity took over, they would sort of half flop down the surface - pausing to stick in places. It sort of gave the appearance that they were walking.
It wouldn't take long for a brand new, squeeky-clean w.w.w. to become a giant dust ball.