FIG. 1 is a front, top perspective view of a refractory brick showing my new design; FIG. 2 is a back, top perspective view thereof; FIG. 3 is a top view thereof; FIG. 4 is a front view thereof; FIG. 5 is a back view thereof; FIG. 6 is a left-side view thereof; FIG. 7 is a right-side view thereof; and, FIG. 8 is a bottom view thereof.