Cute, squeezeable toys — from Sophie la Girafe to the humble rubber ducky — can fill up with a slimy black mould if moisture gets inside. Fortunately, it's possible to clean them, and even to prevent the slime from taking hold in the first place.
As scary as the mould is, it's not dangerous to your kid's health, so relax and grab the bleach. As this video shows, you can clean the toys inside and out with a bleach-and-water mix, and then plug up the hole with a dab of hot glue.
If your bath toys are too far gone, we understand if you'd rather pitch them and buy new ones. In that case, consider shopping for toys that don't trap water.