octagonal is part of:

octagonal contains:
    50%  half-octagonal
    25%  quarter-octagonal

Full expansion for octagonal:
   100%  10x10 Open-Octagonal Plate
   100%  10x10x4 Octagonal Dome Bottom
   100%  10x10x4 Octagonal Dome Top
   100%  2x2x1.6 Octagonal Cone Brick
   100%  2x2x3.3 Octagonal Brick
   100%  2x3x1.6 ZigZag-Octagonal Brick
   100%  6x6 Open-Octagonal Plate
   100%  6x6x2 Oct. Dome w/Hinge
   100%  6x6x2 Oct. Dome, Hydronauts
   100%  6x6x2 Oct. Dome, Stingrays
   100%  6x6x2 Octagonal Dome
    90%  2x2x3.3 Corner Octagonal Brick
    80%  2x2 Plate w/ Rod Frame, Octagonal
    80%  2x2x3.3 Octagonal Brick w/Side Studs
    80%  6x6 Octagonal Plate w/ 4 Clips
    80%  6x8x3 Oct. Dome Half-Bottom
    80%  6x8x3 Oct. Dome Half-Top
    70%  6x6x1 Octagonal Hinging Dome Porthole
    50%  3x6 Half-Octagonal Plate
    50%  3x6x6 Half-Octagonal Castle Wall
    50%  4x8x2 Half-Octagonal Castle Turret
    25%  3x3 Quarter-Octagonal Plate
    25%  3x3x6 Qtr-Oct. Castle Wall w/ Bricks
    25%  3x3x6 Quarter-Octagonal Castle Wall
    25%  6x6 Octagonal Umbrella
    25%  6x6 Quarter-Octagonal Plate
    25%  6x6x6 Qtr-Oct. Castle Wall w/ Window
    25%  7x7x2.3 Qtr-Octagonal Castle Turret
    20%  10x10 Quarter-Open-Octagonal Plate
    20%  6x6x3.3 Sloped Hingeable Cockpit
    10%  4x10 Cut-Corner Brick