No, it is an activity.
You don't really have to - do it whenever you feel like it.
The hymen does not break, it can stretch or be torn but this would be as a result of vaginal penetration. If you masturbate using internal penetration, such as with fingers or sex toys, then the hymen may tear but usually this will only occur if penetration is rough or forced.
All Microbes are not harmful. All virus are harmful. Some bacteria are harmful
some are harmful but some are not harmful
No they are not harmful.
more harmful, most harmful
lion are useful and harmful
If you need help I recommend you type in the specific question you need help with
It is not harmful to animals but it can be harmful/fatal to children
it is very harmful or harmful depending on your body
Harmful is an adjective.