One circle makes a Circle.
Two circles make a Vesica Piscis.
Three circles make a Trinity--and three Vesica Piscis.
Here is the pattern more commonly seen in a religious setting. They're within Saint Mary's doors and windows.
And here's a little rough sketch of an idea I have for my egg tempera workshop. I will redraw this up properly with a board and t-square and compass. I suppose I could scale the pear anywhere. Suppose it was only a third that size? Then there's the matter of lighting. I may have to build models...