They are earrings. The holes seen on the ears of the clay figurine are for earrings and appear on many of clay figurines. They may have pierced the ears with a bone needle and gradually broadened the hole with a twig or the like. This kind of method is seen in many ethnic tribes all over the world.
It is not rare to find earrings that are eight-centimeters in diameter (in which case the holes in the ears would need to be about four centimeters big). The earrings may have started with a size of 1 cm but grew as the pierced holes gradually became bigger, or this large size may be a result of competition in size. The size and design may have been a topic of interest in Jomon fashion.
Earrings were made lighter by giving them a ring shape, such as those in No. 2 (top, p. 71) and/or by elaborating exquisite openwork, such as the one in No. 3 (bottom, p. 71).
Refuse, produced when sculpting clay to make the earrings, has been excavated along with the earring of No. 3.