Chirality is the phenomenon that, like hands, asymmetric objects can come in two mirror-image forms. Many organs and entire organisms are asymmetric. However, in most species, only one of the two mirror-images actually exists. In snails, for example, almost all species are entirely clockwise or anti-clockwise coiled.
Rarely do both mirror-image forms occur mixed in the same population (a situation known as 'antisymmetry'). I am working on understanding the causes for this rarity of antisymmetry and the causes for antisymmetry when it does occur, in various groups of organisms, notably Amphidromus treesnails and insect genitalia.