Massive stack of triangles that resembles arrows pointing both up and down.
page8-157.png page2-34.png page2-131.png page6-72.png
page6-143.png page8-157.png page5-100.png page7-80.png page2-131.png page3-71.png page5-224.png page2-34.png page5-190.png page6-72.png
Wrong. The correct arrow shaped stack of triangles is diagonal.