A tower of books with a almond- or vaginal-shaped opening

By VitVit (Own work) [CC BY-SA 4.0], via Wikimedia Commons
A sculpture, interactive, sometimes described as a tower, sometimes a tunnel, in the Prague Municipal Library. The artist’s material is old books. The form is suggestive – is it a mandorla? a yoni? a “vesica piscis”? Any of those would be an opening for further … ideas
Accessed 01-17-18