The spiral or concentric circles motif appears prominently on many edan. Informants offered two different but related interpretations for it.

According to some, it represents the spin (ranyinranyin) of the cone-shaped bottom of the small snail shell (okoto), a children's toy associated with increase, dynamic motion,and, by extension, with the transformatory power of Esu, the divine messenger who mediates between the orisa and Ile.

Others identify the motif with the motion of a whirlpool, signifying the expansive power of Olokun, the goddess of the sea and abundance. Since Oduduwa reportedly created habitable land out of the primordial sea at Ile-Ife (Idowu 1962:22; Ojo 1966:194), it is apparent that Earth and Water are, in essence, two aspects of the same phenomenon venerated by the Gelede society as Iya Nla (Mother Nature), alias Olokun ajaro okoto ("The sea goddess, who whirls like okoto").

Indeed, the snail shell motif occurs on Ogboni doors (Dobbelmann 1976: pls. 156).[31] Moreover, black mud from a river or lake is a vital part of the ingredients used in consecrating an altar to Ile, and a fish-legged figure often dominates the relief decoration on Ogboni doors (Dobbelmann 1976:156-57) and drums (Ojo 1973:50, pl. 1), thus linking the terrestrial realm with the aquatic. In any case, as a metaphor for the rhythm of life, and increase (iresi), the spiral or concentric circles motif reinforces the ritual power of edan Ogboni.

Babatunde Lawal on the edan ogboni sculpure of the Yoruba of Nigeria in "Aya Gbo, Aya to:New Perspectives on Edan Ogboni",African Arts,vol.28 ,no.1.Winter 1995,364-49;98-100.