Born in Ascoli Piceno, the son of the Florentine sculptor Fulgenzio Morelli, who also trained Lazzaro's cousin, the artist Giuseppe Giosafatti.
[1] He participated in Bernini's Funereal Monument for Pope Alexander VII Chigi, found in St. Peter's Basilica.
He is said to have sculpted the horse and the lion for Bernini's Fountain of the Four Rivers in Piazza Navona.
[2] Lazzaro also sculpted the statue of Benignity for the tomb monument of Clement X in St. Peter's.
He also completed some of the saints in the roof-line of the external colonnades of Piazza San Pietro.