The letter '且', which is a part of the character of '祖 (so)' as in Doso-shin indicates a penis in ancient Chinese hieroglyphic characters left on bones and tortoise carapaces and Kinbuntai (Chinese bronze inscriptions).
道祖神の「祖」の漢字のつくりの「且」は、甲骨文字、金文体上では男根を表している。