Rubber Duckies

I have a little problem that I thought I would share with all of you, appealing to your wisdom so that maybe one of you will be able to help me. We have several little rubber duckies that my kids love to play with during bathtime. They're the little plastic yellow ones that have the hole in the bottom of them so they squeak when you squish them. That means they can also get water in them if squished underwater, getting water trapped inside. Katy especially loves this, because she loves to watch the water stream out of the little hole when she then squeezes them above water. My problem comes after bathtime is over. I can never get all of the water out of them. I didn't worry too much about it at first, but the other day, as I was bathing my kids, I noticed some yucky greenish stuff floating in the water with them. I watched Katy as she played with the rubber duckie and realized the yucky green stuff was coming from inside the duck. When she squeezed the water out, the green stuff came with it. I think that it was mold. But I can't figure out how to clean the inside of a rubber duckie! And how do you get all the water out so that it dries properly and doesn't mold? I'm so confused. At the moment, they just don't get to play with rubber duckies in the bath. Any suggestions?