How do you remove mould from silicon?

I have what I think is a silicon cover for my containers. It comes in various sizes for various size dishes.

It's a semi-clear stretchy material that I use to cover my water pitcher.

Over the months I notice little black dots of what looks like mould. I tired scrubbing it out but it seems imbedded right into the material.

I also have a thermos which I only store water and it has a similar silicon material to seal the cap edge. It, too, has black mould which I cannot scrub or boil out.

Is it possible to remove the mould or should I just throw out these things and never buy silicon again?

I don't seem to have a problem with my silicon spatulas. Mind you, these are dried after washing and the silicon is not as malleable as the above.