Okay, I have an idea. A character who lost his arm, went into a trial for a procedure they thought could help him regrow an arm but it grew back as a long, tentacle like thing. He has full control over it, it has nerve endings and muscles but no bones. He can use it as a whip, or wrap around people or objects and grab them from up to about 10 feet away (10 feet being the left of the tentacle when it's fully unravelled, normally he keeps it wrapped aroundh himself). I have a basic idea for the backstory forming in my head.