A square with a single diagonal seam cut from one corner toward the two adjacent sides, this unit is a basic patchwork technique with roots stretching back centuries, structurally related to the corner-clipping and stitch-and-flip methods used in blocks like Flying Geese since at least the 1800s. The resulting triangle radiating from the corner gives the unit its beam-like look. It functions as a building-block unit rather than a standalone design, showing up as a component inside larger quilt blocks rather than on its own.