Image Item No. Description  20953  Brick, Round 2 x 2 Sphere with Stud / Robot Body Catalog: Parts: Brick, Round  49308  Brick, Round 3 x 3 x 1 1/3 Dome Top - Open Stud Catalog: Parts: Brick, Round  73111  Brick, Round 3 x 3 x 2 with Recessed Center and Axle Hole Catalog: Parts: Brick, Round  65138  Brick, Round 4 x 4 x 2/3 Dome Top with Hole Catalog: Parts: Brick, Round  65617  Brick, Round Corner 3 x 3 x 1 without Studs Catalog: Parts: Brick, Round