I've always thought that magatama seem embryonic and innocent. The "bumps" seen on some magatama may represent compound magatama, or magatama within magatama, with multiple interesting implications for the human spirit that compound magatama may represent.
Imperial Regalia of Japan
("Sanshu no Jingi", or "Three Sacred Treasures" of Japan)
The Imperial Regalia of Japan included a stone magatama. Remember, in Japan the royalty were officially considered descended from the gods until after the end of WWII.
The regalia represent the three primary virtues: valor (the sword), wisdom (the mirror), and benevolence (the magatama).
The three sacred treasured are located in Shinto temples in Japan to this day. Since ancient times, the presentation of these items were a central part of the imperial regalia ceremony. This ceremony is not public, and the actual items are by tradition only seen by the emperor and certain priests. Because of this, no known photographs or drawings exist.
The illustration of the three sacred treasures is conjectural, but the closeup shown at top is from an actual archeological find of a small magatama deposited during the Jomon period in ancient Japan.
Ancient (paleolithic) people left many nicely drawn characatures of humans. The simplified cartoon style face appears typical in various examples of stone remnants. Was this style adopted because it was easier to carve?
Though we know very little about them, people apparently were people then, just as we are people now. At right is an ancient "ganja" figure, still represented similarly in modern anime.