The achene is elongated and flat-oval, approximately 6 mm in length and about 3 mm in diameter at the middle. The outer skin is grayish-brown with several slightly raised longitudinal stripes, one of which is more prominent in the center. The entire surface has sparse spots, resembling a dense network pattern. One end is slightly narrow and curved, with a small light-colored dot at the top; the other end is blunt, round, and somewhat wider, featuring a small concave pit. The longitudinal surface is slightly raised, with smooth, round, and thick edges. The outer skin is relatively hard, and when broken open, the seed kernel splits into two lobes, grayish-white in color and rich in oil. It is odorless and has a slightly bitter taste. Those with large, plump grains and grayish-brown outer skin are considered superior.