growth

I've got some green plant-like stuff (it might be a kind of moss but it looks too small and I'm no botanist...) growing in the velvet seal of my driver's-side window. I've tried rubbing the stuff off, but it seems too resistant to physical attack and I'll probably end up damaging the seal...

I clean and polish my car fairly regularly but just recently i have noticed that there is a green moss like growth on the window rubber of one of the rear doors (only 'grows' on this door :think: )......I have tried lots of things to remove it but it keeps coming back, any ideas how to get rid...