A gridiron is a metal lattice for broiling or grilling food (or, in the case of St. Lawrence, saints). It’s a period charge, found in the canting arms of the Worshipful Company of Girdlers, 1454 [Bromley & Child 109]. The gridiron is palewise, handle to base, by default. See also portcullis, strike.
Domenico Barbiere da Mantova bears as a badge: A gridiron sable.
Jean Yves de Chierebourg bears as a badge: A gridiron argent.