I would rinse them, give them a dip, rinse again, try and QT them in a plastic container for a few days, checking for hitchhikers a few times daily?
Don't put it in your lake.... Unless it's a native speciesThere are multiple kinds. There's brown and one thats kind of like a yellow red.
I decided not to risk it. I issued a refund, the seller gave me my money back with no request to send back the item. So I'll probably put it in my lake, let it grow there, and order some tissue cultured grass for my tank. It's way more expensive but it will have to do...