I have an Invisalign question?!

I have an Invisalign question?

I am on my first set of invisalign aligners, and every time I take them out, I notice some white stuff on them. I don't know what this is or if it's from my teeth, but when I try to clean it it doesn't come off. Can someone please advise me on how to get rid of it?

This is going to sound silly but use a denture cleaner. Take one of those fizzy tablets, add water and soak your aligner for a few minutes. See if that doesn't help.