Bernini was called upon to produce far more sculpture than he could ever carve himself, and most works of his maturity were executed by others to his designs. This is a study for a fountain in the Palazzo Ducale at Sassuolo, near Modena. The sea-god Neptune stands astride two shells supported by sea-centaurs. An assistant prepared clay models on the basis of Bernini’s drawings, from which local craftsmen executed the fountain in stucco.