Good news for homosexual male snails living off the coast of Western Australia, as the female sex of the Thais Orbita species have all grown rather large "members" on their heads. Sadly, the head-peni have formed due to chemical reactions.
While you're right in remembering from sordid science classes that snails are usually hermaphrodites, this particular species of snail actually does have male and female sexes, much like the human race. Unlike you and I, however, we do not have penises on our foreheads (well, most of us anyway - I can't speak for these people), whereas the male gender of the Thais Orbita does.
Due to contact with the chemical Tribytyltin, last used in 1991 in boat paint, the female snails' hormones have been all messed up, and as a result they've grown penises on their heads.
Image Credit: AnnieGreenSprings