Adamantane (tricyclo[220.127.116.11,7]decane) is a cycloalkane and also the simplest diamondoid. Check out Wikipedia. Cyclohexane isn't flat: its thermodymanically favorably configuration "chair" (it looks like a beach chair) four such fit together to make a stunningly symmetrically three-dimensionally configuration. One thing we certainly know is that oddly stable, totally hydrocarbon compound can have medical significance.
An aminoadamantane is a drug; there are other derived drugs.What is going on here??