fuzzy algae on snail's shell
 

one of my turbo snails has purple fuzzy algae growing on his shell. Should I try to clean it off or is it ok just to leave it? I don't have any of this algae anywhere else in the tank

Nah, I'd say leave it alone, scrubbing the shell will still leave stubble and it'll grow back anyway. My snails just clean each other when they happen to meet. Sometimes that won't happen for a while, and other times, they'll congregate in a spot to do each other a favour.

Yup just leave him be. Any other algea eaters in the tank will remove as Lenny said.