A stem may comprise a circular base, a plurality of outer ears, and a plurality of outer uprights. The circular base may have a circular outer perimeter centered on a center point of the circular base. The plurality of outer ears may protrude outwardly from the circular outer perimeter. The plurality of outer uprights may be respectively connected to each of the plurality of outer ears at a bottom end of each of the plurality of outer uprights. The plurality of outer uprights may be substantially parallel with each other and may be substantially perpendicular to the circular base. The stem may be configured to allow an additional stem to mateable stack inside the stem. The additional stem may be rotated (with respect to the stem) an incremental amount such that sides of outer ears of the additional stem may respectively contact sides of the outer uprights of the stem.