The length and composition of the beams varied between beams. (A) Plot of calcium content as a function of position along the beams, with zero set as the center of the gradient region. The length of the beams ranged from 41 to 99 μm. (B) The length of the mineralized, unmineralized, and graded regions were determined from the plot in A and are shown normalized to beam length. Dark shades represent mineralized, medium shades represent graded, and light shades represent unmineralized. These variations in the amount of each phase between beams are expected to have mechanical consequences.