Determine the basic shape. Most Texas arrowheads fit into one of these 10 categories: articulate (fish-shaped), basal-notched (notches at the bottom), contracting stem (large triangle on top, smaller triangle at base), corner-notched (notches on bottom corners), lanceolate (long and thin without notches), leaf (wide in middle, narrow at the ends), side notched (notches on sides), expanding ...