Piero Della Francesca’s Brera Madonna, detail of the niche. Executed in 1472-1474. Pinacoteca di Brera of Milan. / The shell was a symbol of the new Venus, Mary, and the egg is generally considered a symbol of the Creation.
Piero della Francesca, Detail from the cycle of frescoes of the "Legend of the holy Cross" in the choir of the Basilica of San Francesco in Arezzo. c. 1452-66
Madonna and Child with Saints (Montefeltro Altarpiece) : PIERO della FRANCESCA : Art Images : Imagiva
Piero Della Francesca
Piero della Francesca: The Madonna of Mercy (1460)