As the word 'suribachijo' (shape of suribachi) shows, it is shaped like an inverted circular cone, which is narrow at one end, has sloping sides, and is round at the other end.
形状は「すり鉢状」という言葉があるように、円錐を逆にしたような形で、下がすぼまり上に行くほど径が大きくなる。