Carvone forms two mirror image forms or enantiomers: S-(+)-carvone smells like caraway. Its mirror image, R-(–)-carvone, smells like spearmint. The fact that the two enantiomers are perceived as smelling differently is proof that olfactory receptors must contain chiral groups, allowing them to respond more strongly to one enantiomer than to the other.
(Source: Wikipedia, s.v. Carvone.)