Female figures prominently displaying the yoni [female genitalia] as a vesica piscus [Mandorla] were once common ornaments of Irish churches built before the sixteenth century. As a rule the sheila-na-gig was carved into the keystone of a window or doorway arch. Undoubtedly it was a protective sign left over from pre-Christian Goddess worship. Figures of the same type were found throughout Europe as cathedral decorations, on the capitals of columns, at the ends of ceiling beams, and so forth. Squatting Goddess figures almost identical to the Sheila-Na-Gig guarded the doors of temples in India. (refer; "The Woman’s Dictionary of Symbols and Sacred Objects," – section on Sheila-Na-Gig)
Quoting again from Ernest L. Martin, Anatomy of a Church:
You will often see Mary and/or the supposed "Jesus" within a glorified Mandorla symbol. Note the following examples.
Then there are the visual parallels between:
1. Planets revolving around the sun in our solar system and particles that orbit the nucleus of an atom.
2. Similarities between the stars in our galaxy and a DSNA spiral. See images below:
It would seem to me there is some form of cosmological hierarchy. And if there is some form of lost ancient knowledge, then it likely has to do with reproduction!