Amongst the many carvings peering down at you from church doorways and castle walls you may one day encounter a figure to inspire feelings of shock, disgust, confusion and more than a little intrigue. Brazenly displaying all their assets, these unusual carvings known as sheela-na-gigs have mystified scholars and inspired artists for centuries. But what they are and why are they there in some of the last places you'd expect to see an image that could arguably be considered lewd, is still very much open to debate.