Dd2 has some of those bath toys which are silicone animals with little holes that let you suck up water then squirt it back out. I just noticed her sucking on the hole of one and when I squeezed it some black gunk came out 
I'm worried now about exposure to mould! It was only for a second and I doubt she sucked hard enough to actually get any of the stuff in her mouth but I'm freaking out a bit. Needless to say the toys will be going in the bin. She's sleeping soundly now but should I be concerned?